Mixer Stage Compensation Circuit for IM3 Amplitude and Phase Tuning
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Solution Overview
Problem
Existing compensating circuits in mixer stages, particularly those based on the Gilbert cell, face challenges in reliably compensating unwanted intermodulation products over a wide range of operating parameters, including frequency and temperature, due to limited flexibility in setting bias currents and amplitude adjustments.
Innovation Solution
A compensating circuit with a compensating input stage that allows for independent control of the amplitude and phase of the input signal, using a voltage divider with resistive and/or capacitive components, and optionally controllable elements, to produce optimal IM3 signals for compensation, thereby enhancing flexibility and matching across various operating conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a compensating circuit uses a differential stage with bias current control to compensate intermodulation products, then the compensation can be adjusted, but the flexibility is limited and reliable compensation over a wide operating parameter range is difficult to achieve
Solution Approach 1:
The patent implements dynamic control of the compensating signal by introducing a controllable voltage divider that can adjust the amplitude and phase of the signal fed to the differential stage. This allows the compensation parameters to be dynamically adapted to different operating conditions (frequency, temperature, input signal level), resolving the contradiction between limited adjustment flexibility and reliable compensation across wide operating ranges.
Solution Approach 2:
The patent changes the parameters of the input signal to the compensating stage by using a voltage divider with controllable resistive and/or capacitive components. This enables independent control of amplitude and phase parameters, providing the flexibility needed to maintain reliable compensation across varying operating conditions without being constrained by bias current control alone.
2Reliability
If the amplitude of the input signal to the compensating stage is increased to maximize IM3 product generation, then compensation effectiveness improves, but circuit complexity and design effort increase
Solution Approach 1:
The patent introduces a voltage divider as an intermediary component between the input signal and the compensating stage. This voltage divider acts as a mediator that can independently control the amplitude and phase of the signal fed to the differential stage, allowing optimal IM3 product generation without directly increasing the complexity of the core compensating circuit. The voltage divider provides a simple yet effective means to achieve the desired signal conditioning.
3Reliability
If bias current is increased to improve compensation performance, then intermodulation product compensation improves, but power consumption increases
Solution Approach 1:
The patent enables dynamic control of the compensating signal amplitude through a controllable voltage divider, allowing the system to achieve optimal compensation performance without continuously operating at high bias currents. The voltage divider can adjust the signal level to match operating conditions, maintaining effective compensation while reducing power consumption compared to always using high bias current.
Data Source
AI summary
A compensating circuit for a mixer stage is provided, wherein the mixer stage has an input stage to which an input signal for mixing can be applied and has, following the input stage, a switching stage for mixing a differential input signal—obtained from the input stage as a function of the input signal—with an oscillator signal, wherein the input of the compensating circuit can be connected to an input signal terminal of the input stage and the output of the compensating circuit can be connected to an input signal terminal of the switching circuit at which the differential input signal obtained by means of the input stage is present, and wherein a compensating signal obtained by means of a compensating stage of the compensating circuit, in particular for compensating intermodulation products, can be produced by the compensating circuit at its output. The compensating circuit has a compensating input stage with means for influencing an amplitude and/or phase of the input signal, by which means the compensating stage can be supplied with a modified input signal.