Skyworks Solutions, Inc.

Conexant Systems, Inc.

James Cherry

Florinel G Balteanu

William Martin Snelgrove

Mark M Cloutier

Neil Birkett

Ashok Swaminathan

A low power IF strip architecture suitable for Zero-IF (ZIF) or low-IF (LIF) radio receivers for filtering and amplifying a received signal. The apparatus includes a plurality of sequentially connected complex filter/amplifier stages. Each stage includes a complex filter having one or more poles and an automatic gain controlled amplifier (AGC). Each AGC may be feedback or feedforward with fixed minimum and maximum gains. Each stage further includes a control circuit that produces a gain control signal for controlling the amplifier gain within the fixed minimum and maximum gains as a function of a projected amplitude level. The received signal passes through multiple stages of filtering and controlled amplification to attenuate the interfering signal and amplify the desired signal. This is done at a restricted level in each stage such that the circuits in the stages operate at efficient power saving levels. The individual gain control signals from each stage are summed in a received signal strength indicator to provide the overall gain of the apparatus. The overall gain when taken with the amplitude of the apparatus output signal determines the original strength of the desired received signal.

Complex filtering/AGC radio receiver architecture for low-IF or zero-IF

Wireless communications devices must handle a wide range of useful signal levels and must also cope with large interfering signals of nearby frequencies. They often use transconductance amplifiers/filters as building blocks as such amplifier/filters exhibit good characteristics of both amplification and filtering. The transconductance cells described make use of feedbacks which involve no signal conversions. As the result, the cells have high linearity and yet can operate at low voltage.

Low-voltage transconductance amplifier/filters

Disclosed is a frequency-locked loop (FLL), which attempts to bring about frequency and phase synchronization between two signals over the control bandwidth of the loop: a reference signal and a voltage-controlled oscillator (VCO) signal. For example, the FLL employs a reference signal generated by a crystal oscillator of frequency f and a VCO signal generated by the oscillations of an unquenched SRG resonator with tunable resonant frequency f . These signals are connected to the inputs of a phase/frequency detector (PFD) which produces output pulses in response to the relationship between f and f . These pulses are applied to a loop filter (LF) which creates a voltage using some kind of charge-storage element. This loop filter voltage is a so-called error voltage whose value is used to control the frequency of the resonator to bring the reference signal and VCO signal into phase synchrony.

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Ottawa, Canada

James Cherry