Raytheon Company

Ricky Y Chen

Lloyd Frederick Linder

Don C Devendorf

Matthew S Gorder

Erick M Hirata

Robert T Narumi

Phung N Phan

A transceiver has a digital signal processor which can insert calibration signals of known level and frequency into transmitters for calibration and correction of transmitter parameters. An output of the calibrated and corrected transmitter is subsequently coupled into a calibration mixer along with a mixing signal (e.g., from a local oscillator generator. The outputs of the calibration mixer have known levels and frequencies and are inserted into receivers for calibration and correction of receiver parameters.

Self-calibrating, self-correcting transceivers and methods

A 'gain control differential pair' (GCDP) conducts current in response to a differential drive signal, with the gain of a signal path formed via the current circuit of one of its transistors controlled by the drive signal. The GCDP is preferably driven with a drive circuit that receives a symmetrical input signal and produces an offset differential drive signal which has the effect of keeping one of the GCDP's transistors turned off over a wider portion of a symmetrical input signal's voltage range, thereby reducing GCDP-caused noise. One or more GCDPs are implemented as part of a Gilbert mixer to regulate the amount of RF current that flows between the mixer's output and input stages, which eliminates the need to provide gain control in other circuits fed by the mixer. When driven with an offset drive signal, the Gilbert mixer simultaneously provides gain control, low distortion, low power consumption and excellent LO/RF isolation.

Differential pair gain control stage

A low voltage analog front end (AFE) includes a differential transistor pair which converts an input voltage, typically A.C.-coupled to the pair's control inputs, to a differential current. Impedance networks connected to each transistor's control input are joined together at a common node, and a current source is connected to the node which causes DC bias currents to be mirrored through the pair's current circuits, so that the AFE's differential output current comprises a differential current produced by the pair in response to an input voltage and superimposed on the DC bias currents. The current source preferably generates mirrored currents which are larger than its reference current to linearize the pair's response and to provide the AFE with a wide dynamic range. An input to the AFE sees a low impedance which is about equal to the sum of the impedance networks, which can be resistive or complex as needed. The AFE has widespread application as a front end circuit, serving as a low voltage input stage for a Gilbert mixer, for example. By generating bias currents via the pair's control inputs, supply voltage headroom requirements are reduced, improving a system's dynamic range and/or enabling the use of lower voltage power supplies. The AFE can be configured as either a differential or single-ended voltage-to-differential current converter.

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Irvine, CA, United States of America

Ricky Y Chen