Multi-Input Gilbert Cell Mixer With Selectable Gain Stages
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Solution Overview
Problem
Conventional Gilbert cell multiplier circuits in receivers and transmitters require cascading external switching and gain blocks, leading to performance degradation in noise figure and linearity, and are not suitable for applications where only one of multiple inputs needs to be multiplied.
Innovation Solution
A multi-input Gilbert cell mixer design with integrated stage select circuitry allows for the selection and activation of only one input/gain stage at a time, eliminating the need for a cascaded M:1 switch and variable gain amplifier, while maintaining linearity and noise figure performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If cascading external switching and gain blocks are used in receivers and transmitters, then multiple input paths and gain states can be achieved, but noise figure increases and output intercept point (linearity) decreases
Solution Approach 1:
The patent combines multiple input/gain stages and the Gilbert cell mixer into a single integrated circuit device. The stages are merged such that multiple differential pairs share common biasing and control circuits, allowing multiple input paths and gain states to be achieved without cascading external blocks, thereby maintaining noise figure and linearity performance.
Solution Approach 2:
Each differential pair in the integrated device is designed to be multi-functional, capable of operating in different gain states and handling different input paths. The stage select circuitry enables any differential pair to be activated based on control signals, providing universal functionality for multiple input/gain configurations within a single device.
2Adaptability or versatility
If conventional Gilbert cell configurations are used with multiple inputs, then all inputs must be multiplied at once, but this is not suitable for applications where only one of multiple inputs is desired
Solution Approach 1:
The patent implements dynamic control of multiple differential pairs through stage select circuitry. Control signals dynamically enable or disable specific differential pairs based on which input path should be active. This dynamic switching allows selective activation of individual inputs without requiring all inputs to be multiplied simultaneously, providing operational flexibility.
Solution Approach 2:
The integrated device segments the multiplication function across multiple independent differential pairs, each capable of independent activation. The stage select circuitry divides the control of multiple inputs into separate controllable stages, allowing individual selection and activation of specific input paths rather than requiring simultaneous processing of all inputs.
3Ease of operation
If M:1 switches and variable gain amplifiers are cascaded externally, then input selection and gain control are achieved, but device complexity and system performance degradation occur
Solution Approach 1:
The patent merges the functions of M:1 switching and variable gain control into the integrated device structure. The stage select circuitry combines input selection and gain state control in a unified architecture, eliminating the need for separate external switching and amplification stages, thereby reducing overall device complexity while maintaining operational ease.
Data Source
AI summary
Multiple input and/or gain stage Gilbert cell mixer designs are disclosed. The designs allow one input to be turned on at a time, and are suitable, for example, for use in receiver and transmitter applications. In addition, the designs allow for the inputs of the multi-input Gilbert cell mixer to be connected together, thereby allowing for switching of gain states within the Gilbert cell mixer. The mixer design may include, for example, a Gilbert cell mixer stage, and a plurality of input/gain stages. Each input/gain stage has its output connected to the input of the mixer stage, and is configured for receiving an input signal and applying a gain factor to that input signal to provide a signal for mixing with the LO. Each input/gain stage is configured with stage select circuitry for enabling or disabling that stage, so that only one input/gain stage is active at a time.