# US 7,746,151 B2 · Variable gain mixer

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- Number: US 7,746,151 B2
- Document ID: US7746151B2
- Status: Granted
- Kind: B2
- Application number: 11/993,001
- Filed: 2006-06-30
- Published: 2008-12-25
- Granted: 2010-06-29
- Earliest claimed: 2005-07-01
- Assignees: Fci
- Inventors: Sung Ho Beck
- Web page: https://patentgrep.com/patent/US7746151B2

## CPC

- H03D 7/12: by means of semiconductor devices having more than two electrodes (H03D7/14 - H03D7/22 take precedence)
- H03D 7/1433: {using bipolar transistors (H03D7/145 takes precedence)}
- H03D 7/1458: {Double balanced arrangements, i.e. where both input signals are differential}
- H03D 2200/0019: Gilbert multipliers
- H03D 2200/0025: Gain control circuits
- H03D 2200/0027: including arrangements for assuring the same gain in two paths
- H03D 2200/0043: Bias and operating point
- H03D 2200/0088: Reduction of intermodulation, nonlinearities, adjacent channel interference; intercept points of harmonics or intermodulation products
- H03D: DEMODULATION OR TRANSFERENCE OF MODULATION FROM ONE CARRIER TO ANOTHER (masers, lasers H01S; circuits capable of acting both as modulator and demodulator H03C; details applicable to both modulators and frequency-changers H03C; demodulating pulses H03K9/00; transforming types of pulse modulation H03K11/00; coding, decoding or code conversion, in general H03M; repeater stations H04B7/14; demodulators adapted for AC systems of digital information transmission H04L27/00; synchronous demodulators adapted for colour television H04N9/66)

## Abstract

The mixer includes mixers constructed with variable gain amplifiers having two transistor pairs Qp+/Qp− and Qn+/Qn− to have a predetermined gain by using LO+ and LO− signals; and LO bias circuits connected to have bias voltages different from each other with respect to the LO+ and LO− signals of the mixers and share an input signal.

## Claims

### Claim 1

A variable gain mixer comprising:
mixers constructed with variable gain amplifiers having two transistor pairs Qp+/Qp− and Qn+/Qn− to have a predetermined gain by using LO+ and LO− signals; and
LO bias circuits connected to have bias voltages different from each other with respect to the LO+ and LO− signals of the mixers and share an input signal,
wherein the LO bias circuit is constructed with an operation amplifier, a first resistance connected to an output of the operation amplifier, and a second resistance connected between an output of the first resistance and an input of the operation amplifier to remove a capacitive load to the input of the operation amplifier.

### Claim 2 (depends on 1)

The mixer according to claim 1, wherein the LO bias circuits have bias voltages different from other with respect to the LO signals.