JPH0365808A - Mixing circuit - Google Patents

Abstract

PURPOSE:To save power consumption of the circuit by connecting transistors(TRs) in series and inputting a signal from a base of respective TRs. CONSTITUTION:A local oscillation signal is applied to a base of a 1st TR 1 via a capacitor 2. An emitter of a 2nd TR 4 connects to a collector of the 1st TR 1 via a resistor 3A capacitor 5 is connected from the collector of the 1st TR 1 to a base of the 2nd TR 4, a signal for frequency conversion such as a local oscillation signal or a reception signal is inputted from an emitter of the 2nd TR 4 via a capacitor 6, a tank circuit 7 is provided to the collector of the 2nd TR 4 and tuned to a required frequency and the result is outputted. The two TRs 1, 4 are connected in series, a signal is given to the base of the TRs 1, 4 and an output is obtained from the collector of the 2nd TR 4, then frequency mixing is implemented while making amplification. Thus, the circuit is made small and the mixing circuit with small current consumption is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION OBJECTS OF THE INVENTION [Field of Industrial Application] The present invention relates to a mixing circuit that performs frequency conversion in a transmitting section or a receiving section of a radio device.

[Prior Art] A mixing circuit is an important part of a frequency conversion circuit of a radio device. In most conventional mixing circuits, two signals are combined at the base or gate of a transistor or FET, amplified by the transistor or FET, and a tank circuit is provided at the output to extract the sum or difference frequency. Conventional circuits often use a circuit that injects two signals into the base of a transistor and mixes them while amplifying them, but this is easily affected by changes in input impedance and consumes a large amount of current. In addition, balanced mixer circuit and dual gate FE
A circuit using T is used.

However, the balanced mixer circuit has a complicated circuit.
Further, the dual gate FET has drawbacks such as high noise.

[Problem to be Solved by the Invention 1] However, recent circuits such as car phones and mobile phones require hybrid circuits that are smaller, consume less power, and have excellent characteristics.

[Objective 1 of the present invention] An object of the present invention is to provide a miniaturized mixing circuit with low current consumption.

Structure of the present invention> [Means for solving the problem] In order to solve the problem, two transistors are connected in series, a local oscillation signal or a signal to be converted is input from the base of each transistor, and a signal to be converted is input from the collector. It is outputting.

[Effect and Example 1 FIG. 1 is a circuit diagram showing an embodiment of the present invention.

A local signal is input from the base side of the first transistor 1 via a capacitor 2. The emitter of a second transistor 4 is connected to the collector of the first transistor l via a resistor 3, and a capacitor 5 for transmitting a signal from the collector of the first transistor l to the base of the second transistor 4 is connected to the collector of the first transistor l. A signal to be frequency-converted, such as a local signal or a received signal, is input from the emitter of the second transistor 3 via a capacitor 6, and a tank circuit 7 is provided at the collector of the second transistor 3 to tune it to the required frequency and output it. are doing. Resistors 8.9, 10, and 11 are bias resistors.

In terms of signal flow, in terms of direct current, the transistors are connected in series, but in terms of high frequency, the signal input from terminal 20 is connected to the first
It is amplified by the transistor l, outputted from the collector, and inputted to the second transistor 4 via the capacitor 5. On the other hand, a signal from the terminal 21 is input to the second transistor 4. The mixed signal is amplified by the second transistor, selected by the tank circuit, and output from the terminal 22. Terminal 23 is a power input.

In this way, by connecting two transistors in series, injecting a signal into the base of each transistor, and outputting it from the collector of the second transistor, the signal is amplified and mixed in frequency. Current consumption is lower than in conventional circuits because the transistors are connected in series.

According to the present invention, the noise is lower than that of other mixing circuits, such as dual gates, and the circuit configuration is simpler than that of a balanced mixer circuit.

Effects of the Invention The present invention reduces current consumption compared to conventional circuits by connecting transistors in series and inputting signals from the base of each transistor, resulting in reduced power consumption of the circuit. . In addition, because there are fewer circuit parts, it can be miniaturized, making it very effective for applications that require smaller size and lower power consumption, such as car phones and mobile phones.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing an embodiment of the present invention. l......First transistor, 2...
...Second transistor, 5...Capacitor

Claims (1)

[Claims] In a mixing circuit that inputs a first signal to the base of the first transistor and inputs the second signal to the base of the second transistor, the collector of the first transistor and the emitter of the second transistor are connected, and the collector of the first transistor is connected to the emitter of the second transistor. A mixing circuit characterized in that a capacitor is connected between the collector of the second transistor and the base of the second transistor, and the output is output from the collector of the second transistor.