Analog Devices,inc.

National Semiconductor Corporation

Byungmoo Min

John A Chiesa

Ekrem Oran

Cemin Zhang

John Poelker

Peter Kim

Systems and methods are disclosed for improved linearity performance of a mixer. An example mixer includes switching circuit elements configured to be switched on and switched off based at least partly on a local oscillator signal and capacitors including a respective capacitor in parallel with each of the switching elements. The mixer is configured to mix the input signal with the local oscillator signal to thereby frequency shift the input signal.

Mixers with improved linearity

An LC tank circuit, such as an LC tank circuit of a step-tuned voltage controlled oscillator, includes an inductor and one or more capacitors. The inductor can be dog-bone shaped with a body, an extension and a chamfered joint to improve current distribution. The body and the extension can extend along different directions. The body can be narrower than the extension, and the extension can be sufficiently wide to interface with a plurality of switched capacitor circuits coupled to different parts of the extension.

Inductor current distribution

An LC tank circuit, such as an LC tank circuit of a step-tuned voltage controlled oscillator, includes a plurality of switched capacitor banks and one or more inductors. A first switched capacitor bank switch in response to a range of control signals used to control the VCO output across a range of frequencies. A second switched capacitor bank can switch in response to a subset of the range of control signals used to control the VCO output across a subset of the range of frequencies. The control scheme for the first and second switched capacitor banks can improves the linearity of changes in the frequency of the output signal of the VCO.

Switched capacitor banks

A die is packaged by flip-chip mounting the die with the active side facing a low loss substrate. A ground plane is coupled to the active side of the die by vias through the low loss substrate. The ground plane is positioned to concentrate high frequency electromagnetic fields in the low loss substrate. A tuning height can be adjusted to tune the center frequency of a circuit in the die.

Circuit with reduced noise and controlled frequency

A method and apparatus are arranged to provide an early comparison scheme for a pipelined ADC stage with a delay circuit. The pipelined ADC includes an amplifier that is biased by a precision bias circuit. The delay circuit includes inverting stages, where each inverting stage includes one or more current sources. The delay circuit is configured to provide a latch signal in response to a clocking signal for the pipelined ADC stage. The latch signal is utilized by one or more comparators for early evaluation of the output of the pipelined ADC stage. The current sources in the delay circuit may also be biased by the precision bias circuit such that variations in amplifier performance are tracked by variations in the performance of the delay circuit. Process, temperature, and power supply related variations in the timing may be minimized by the biasing arrangement of the amplifiers and the delay circuit.

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Lexington, MA, United States of America

Byungmoo Min