JPH02168733A - Front end circuit - Google Patents

Abstract

PURPOSE:To improve a separation rate between reception and local oscillation by using a GaAs dual gate FET for a frequency mixing element, and adding an amplifier, which grounds the second gate of the GaAs dual gate FET on a high frequency basis, to the front stage of a frequency mixer. CONSTITUTION:A received signal from an antenna is amplified through a received signal terminal 11, a received signal matching circuit 15 and a received signal amplifying dual gate FET circuit 17, and inputted to a mixer dual gate FET circuit 18. An output from a local oscillator is amplified through a local oscillating signal terminal 10, a local oscillation matching circuit 14, and a local oscillating signal amplifying dual gate FET circuit 16, and applied to a mixer dual gate FET circuit 18. By grounding the second gate of the GaAs dual gate FET to be the element at the excellent separation degree between inputs and outputs on the high frequency basis, the input/output separation degree is improved, the separation degree between the reception and local oscillation is improved, and the number of the stages of receiving and local oscillating filters can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a front-end circuit of a receiver used in mobile communications and the like.

BACKGROUND OF THE INVENTION Recently, devices in the field of mobile communications such as car phones and mobile phones are rapidly becoming smaller. For this reason, it has become essential to downsize the component parts. The front-end circuits of receivers that handle high frequencies are no exception, and efforts are being made to make them more compact. An example of this miniaturized receiver front-end circuit is the structure described in Japanese Patent Application Laid-Open No. 61-9006. The front end circuit of a conventional receiver will be described below with reference to FIG.

In FIG. 6, 1 is a reception signal terminal, 2 is a local oscillation signal terminal, 3 is an intermediate frequency signal terminal, 4 is a reception filter, 6 is a development film, 6 is a reception matching circuit, 7 is a local oscillation matching circuit, 8
) is a transistor frequency mixing section.

In the following configuration, I will not explain its operation below. A received signal from a receiver (not shown) is applied to a transistor frequency mixer 8 via a receive signal terminal 1, a receive filter 4, and a receive matching circuit 6. On the other hand, the output from the local oscillator is also applied to the frequency mixing section 8 via the local oscillator signal terminal 2, the local oscillator filter 5, and the local oscillator matching circuit 7.

In this frequency mixing section 8, the received signal is mixed with the local oscillator signal.
, is converted into an intermediate frequency signal and outputted from the intermediate frequency signal terminal 3, and operates as a receiving front end circuit.

Problem to be Solved by the Invention 1 - However, in the circuit configuration described above, although the matching circuit has been simplified and the size has been reduced, it is still unsatisfactory, and at the same time, the size of the circuit has increased. 5 ＼-/ The circuit is not suitable for integrated circuits, and the noise figure, that is, the sensitivity of the receiver, is directly affected by variations in the matching state of the reception filter and frequency mixer. However, there were challenges in terms of performance.

The present invention solves the above-mentioned problems of the prior art, by adopting a simple circuit configuration suitable for integrated circuits, and by realizing a circuit configuration with good isolation between input and output.
By improving the degree of separation between reception and local oscillators and reducing the number of stages of reception and local oscillator filters, it is possible to miniaturize the receiver and provide a reception front-end circuit that reduces variations in reception sensitivity. This is the purpose.

Means for Solving the Problems The present invention uses a G a A s dual gate FET as a frequency mixing element, and at the same time, a second gate of a Q A s dual gate FET is provided in the front stage of the frequency mixer. Adding a high-frequency grounded amplifier circuit, and
The above object is achieved by configuring the output matching circuit of the amplifier circuit so as to satisfy the short-circuit condition with respect to the intermediate frequency of the frequency mixer.

Effects The present invention has the above-mentioned configuration, and is a device with good input/output separation. , 7'Uarge-1-FET's second
By grounding the gate at high frequency, the degree of input/output separation is improved12, the degree of separation between the reception and local oscillators is improved, the number of stages of the reception and local oscillator filters is reduced, and all the constituent elements are GaAs FETs. Moreover, by making the output matching circuit of the amplifier circuit satisfy the short-circuit condition with respect to the intermediate frequency of the frequency mixer, the circuit can be simplified and the configuration suitable for integrated circuits can be realized. This achieves miniaturization. In addition, by inserting an amplifier circuit with good separation between the receive filter and the frequency mixer, we can reduce the fluctuation of the receive sensitivity due to variations in the matching state of the receive filter and frequency mixer, and improve the characteristics. This was designed to stabilize the situation.

Drawings from the example? A first embodiment of the present invention will be described with reference to FIG.

FIG. 1 shows the values of the first embodiment of the present invention.
1, which is a block configuration diagram of the end circuit, 10 is a local oscillator signal terminal; 14J reception signal terminal;
Reference numeral 2 designates an intermediate circuit terminal 〒, i 31':, i power supply voltage terminal, 14 a conditioning circuit for local oscillation, and 15 a matching circuit for reception. , 1ebt@2ge-l- and the source are connected, and the DC bias is set with the 7-[resistor, 7h~'2 resistor 1. "---1: 7.7 for local oscillator signal amplification (gate FE
It is a T circuit. 17- is the second gate, +゛,, / -
Connect the DC bias to the gate resistor and source resistor, set the DC bias using the source 4 and the capacitance, and increase li';! The receiving signal terminal A is heavily grounded, done! Legut mouth seven T
It is a circuit. 18 is a dual gate 1-FET circuit for a mixer, which sets the direct current and bias by the first gate resistor, the second N-to resistor, and the source resistor (the source is grounded at high frequency by the capacitor). ('Li 7 Dual gate for amplification F E'l' circuit 16 and mixer terminal -
20 is a dual gate FF for amplifying the received signal.
,']'Circuit 17 and mixer table 1-1"E
Receiver-mixer connection circuit connecting 18 T circuits, 21N
:: 1. This is an F output circuit.

The operation of the configuration as described above will be explained below. A received signal from an antenna (not shown) is amplified through a received signal terminal 11, a received signal matching circuit 15, and a received signal amplification de-Argoux 1-FET circuit 17, so as to satisfy the short circuit condition for the intermediate frequency. The signal is input to the mixer cheal gate FET circuit 18 via the receiver-mixer connection circuit '720 configured as shown in FIG. - output from the local oscillator is connected to the local oscillator signal terminal 10, the local oscillator matching circuit 14,
The local oscillator-mixer connecting circuit 20 is amplified through the dual gate FET circuit 16 for amplifying the local oscillator signal, and is configured to satisfy the short-circuit condition for the intermediate frequency. added to circuit 18. The received signal is mixed with the local oscillator signal in this mixer dual gate 1" ET circuit 18, converted to an intermediate frequency, and then transmitted to the T
Through the I/P output circuit 21, the intermediate frequency signal terminal 12 is also output,
1. Operates as an end circuit.

As described above, according to this embodiment, the second half of the QaA-s dual gate ET, which is an element with good input/output isolation, is
By grounding the terminal at high frequency, the degree of input/output separation is improved, the degree of separation between the reception and local oscillations is improved, the number of stages of the reception and local oscillation filters is reduced, and all the components are connected to G.
By making the output matching circuit of the amplifier circuit satisfy the short-circuit condition for the intermediate frequency of the frequency mixer, the circuit is simplified and the configuration is suitable for integrated circuits. With this, it is possible to downsize the receiver. In addition, by inserting an amplifier circuit with good separation between the receiving filter and the frequency mixer, the receiving sensitivity, which fluctuates due to variations in the matching state of the receiving filter and frequency mixer, can be reduced and the characteristics stabilized. It is possible to aim for

FIG. 2 is a diagram showing a block configuration of a front end circuit according to a second embodiment of the present invention. In Figure 2,
The difference from the configuration in FIG. 1 is that the source resistance of the dual gate FET circuit for amplifying the receiving 1Q signal and the B, F, T circuit for amplifying the local oscillator signal is made common. Items with the same numbers as in Figure 1 are number 1.
It has the same function as the figure. Reference numeral 22 designates a circuit in which the source resistance of the received signal amplifying circuit t'F,T and the local oscillator signal amplifying circuit 22 is made common.

In the following four circuit configurations, the basic operations are the same as those in the first embodiment, so the explanation will be omitted. By using a common resistor, one circuit component can be omitted, and the number of pins can be reduced when integrating the circuit, which is a major advantage.

However, since the input level of the local oscillator signal is usually higher than that of the received signal, if the north resistance of the dual gate FET circuit for amplifying the received signal and the dual gate FET circuit for amplifying the local oscillator signal is made common, Ga If the pinch-off voltage of A-sFET is shallow, the received signal amplification
−γ Lugu 1− J” Current 11 flowing in the FJT circuit,
\-7 is smaller than the current flowing to the dual gate I"BT circuit for amplifying the local oscillator signal, and the desired performance such as NF and gain may not be obtained. Therefore, the current flowing to the dual gate FET circuit for amplifying the received signal It is necessary to adjust the current flowing through the dual gate FET circuit for amplifying the received signal and the current flowing through the dual gate FET circuit for amplifying the local oscillator signal so that the characteristics of each can be obtained. It is useful to change the gate width and pinch-off voltage of the GaAsFET that constitutes the dual-gate FET circuit.

Note that when the pinch-off voltage of the GaAsFETjT is deep, the above phenomenon does not become noticeable and no special adjustment means is required.

Next, a third embodiment of the present invention will be described.

FIG. 3 is a diagram showing a block configuration of a front end circuit in a third embodiment of the present invention. In this example, a circuit configuration consisting of an inductor and a DCC block capacitor is used as the local oscillator-mixer connection circuit or the reception-mixer connection circuit shown in FIGS. 1 and 2. Second
Items with the same numbers as in the figure have the same functions as in Figure 2. 23 is local oscillator signal amplification puergoo) FE
A local oscillator-mixer connection circuit consisting of an inductor shared with the inductor for supplying the drain voltage to the T circuit and a DC block capacitor, 24 is a reception-mixer connection circuit having the same configuration.

In the above circuit configuration, the basic operation is the same as that of the first embodiment, so the explanation will be omitted. DEAL G-1-F for signal amplification
By using a circuit configuration consisting of an inductor that supplies the drain voltage to the E T circuit, an inductor shared with the DC block capacitor, and a DC block capacitor, the circuit configuration is simplified and at the same time a short-circuit condition for the intermediate frequency, which is a good operating condition for the mixer, is realized. are doing.

Next, a fourth embodiment of the present invention will be described.

FIG. 4 is a diagram showing a block configuration of a front end circuit in a fourth embodiment of the present invention. Honjitsu 13 The Henoh style is a monolithic integrated circuit in order to reduce the size of the circuit. Components with the same numbers as in FIG. 2 have the same functions as in FIG. 25 is a dual gate FET circuit for local signal amplification, a dual gate F'BT circuit for received signal amplification, and a dual gate F for mixer.
This is a monolithic integrated circuit for the ET circuit except for the source capacitance.

In the above circuit configuration, the basic operation is the same as that of the first embodiment, so the explanation will be omitted, but the FE
By monolithically integrating T and resistors, Ii"ET with uniform characteristics can be realized with good reproducibility and the circuit can be made smaller. In addition, the Since the emitter-mixer connection circuit and the receiver-mixer connection circuit are not included, an integrated circuit with a high yield can be realized.The dual gates F, I, T, It goes without saying that means for adjusting the current flowing through the circuit and the local oscillator signal amplifying dual gate FET circuit may be provided.

Next, a sixth embodiment of the present invention will be described.

FIG. 6 is a diagram showing a block configuration of a front end circuit in a fifth embodiment of the present invention. In this example, the fourth
Similar to the figure, the circuit is integrated into a J-shape. The difference between FIG. 6 and FIG. 4 is that the scope of the integrated circuit has been expanded to include a local oscillator-mixer connection circuit and a reception-mixer connection circuit. Components with the same numbers as in FIG. 4 have the same functions as in FIG.

26 is a dual gate F'ET circuit for local signal amplification,
The dual gate FET circuit for amplifying the received signal, the dual gate FET circuit for the mixer except for the source capacitance, the local oscillator-mixer connection circuit, and the reception-mixer connection circuit are monolithically integrated.

In the circuit configuration shown below, the basic operation is the same as in the first embodiment, so the explanation will be omitted.
ET, resistance and local oscillator-mixer connection circuit, reception-
By integrating the mixer connection circuit into a monolithic circuit, FETs with uniform characteristics can be realized with good reproducibility, and the circuit can be further miniaturized. Furthermore, since the integration of circuits is progressing, the number of pins of an integrated circuit can be significantly reduced, and a small package can be used. In addition, as in the second embodiment and the sixth embodiment, the dual gate F'E' for amplifying the received signal and the local oscillator signal
It goes without saying that a means for adjusting the current flowing through the "ll" circuit may be provided.Also, in the previous example, the gate voltage of the dual gate FET circuit for amplification and mixing was set to ○■, but it is also possible to apply a bias. Needless to say, it may be used in the same state.

Effects of the Invention As described above, the present invention improves the input/output isolation by grounding the second gate of the GaAs dual gate FET, which is an element with a good input/output isolation, at high frequencies, thereby improving reception, We have improved the degree of separation between the local oscillators, reduced the number of stages in the receiving and local oscillator filters, and made all of the components Oa A,
s F B T, and by making the output matching circuit of the amplifier circuit satisfy the short-circuit condition for the intermediate frequency of the frequency mixer, the circuit is simplified and the configuration is suitable for integrated circuits. By doing so, the receiver can be made smaller. In addition, by inserting an amplifier circuit with good separation between the receiving filter and the frequency mixer, the receiving sensitivity, which fluctuates due to variations in the matching state of the receiving filter and frequency mixer, can be reduced and the characteristics stabilized. This invention was designed to make the system more accessible, and the effects of this invention are significant.

[Brief explanation of the drawing]

1 to 6 are block wiring diagrams of front end circuits in first to sixth embodiments of the present invention, and FIG. 6 is a diagram showing block wiring diagrams of a front end circuit of a conventional receiver. 10... Local oscillation signal terminal, 11... Reception signal terminal, 12
・Intermediate frequency signal terminal, 13...Power supply voltage terminal, 14.
- Matching circuit for local oscillation, 15... Matching circuit for reception, 16.
・Dual gate FET circuit for local oscillator signal amplification, 17・
・Dual gate FET circuit for receiving signal amplification, 18...
Dual gate FET circuit for mixer, 19.23...1
20, 24...Receiver-mixer connection circuit, 21...IP output circuit, 22...Dual gate FET circuit for local oscillator signal amplification with common source resistance and a dual gate FE'll'' circuit for amplifying the received signal, 2
5, 26 ・Monolithically integrated circuit GaA, 5FE
T circuit.

Claims (8)

[Claims] (1) A first GaAs dual gate FET circuit in which the received signal is inputted to the first gate via the first matching circuit, the second gate and the source are grounded at high frequency, and the local oscillation signal is inputted to the second matching circuit. and a second GaAs dual gate FET circuit whose second gate and source are grounded at high frequency, and an output from the first GaAs dual gate FET circuit through a first connection circuit. 1 gate, and a third GaAs dual gate FET circuit having an output from the second GaAs dual gate FET circuit inputted to the second gate via a second connection circuit. (2) The front end circuit according to claim 1, wherein the source of the first GaAs dual gate FET circuit and the source resistance of the second GaAs dual gate FET circuit are common. (3) The first GaAs dual gate FET circuit and the second
3. The front end circuit according to claim 2, further comprising means for adjusting the current flowing through the GaAs dual gate FET circuit. (4) As an adjusting means, the gate width of the second GaAs dual gate FET is adjusted to the width of the first GaAs dual gate FET.
4. The front end circuit according to claim 3, wherein the front end circuit is smaller than T. (5) The front end circuit according to claim 3, characterized in that, as the adjustment means, the pinch-off voltage of the second GaAs dual gate FET is made deeper than that of the first GaAs dual gate FET. (6) The first and second connection circuits are comprised of an inductor that is shared with an inductor that supplies drain voltage to the first and second GaAs dual gate FETs, and a DC block capacitor. Front end circuit as described. (7) The front-end circuit according to claim 1 or 3, wherein the first, second and third GaAs dual gate FET circuits are formed into GaAs semiconductor integrated circuits. (8) The front-end circuit according to claim 1, wherein the first, second and third GaAs dual gate FET circuits and the first and second connection circuits are formed into a GaAs semiconductor integrated circuit.