Single-Gate Mixer and Half-Frequency Divider for Pure Local Signals
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Solution Overview
Problem
In semiconductor integrated circuits for local signal generation in communication LSIs, the purity of local signals is degraded due to the phenomenon of 'pulling' when the oscillation frequency of the VCO is an integral multiple of the transmission frequency, leading to issues with IQ imbalance and nonlinearity, which requires additional amplifier and filter circuits, increasing circuit area and oscillation risks.
Innovation Solution
The integration of an image removing mixer circuit and a ½-frequency divider circuit with a single gate mixer configuration, eliminating the need for separate amplifier circuits and band-pass filters, and utilizing a frequency selective circuit to output only the desired signal, thereby reducing circuit area and power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If an amplifier circuit and band-pass filter are added to remove image signals and amplify desired signals, then signal purity is improved, but circuit area increases
Solution Approach 1:
The patent combines the image removing mixer circuit and ½-frequency divider circuit into a single integrated circuit unit. The mixer circuit performs both image rejection and frequency division functions that were previously handled by separate amplifier and filter circuits, thereby reducing circuit area while maintaining signal purity through the inherent properties of the integrated design
Solution Approach 2:
The integrated circuit unit performs multiple functions simultaneously: it acts as an image removing mixer, a frequency divider, and provides signal amplification through the bias current mechanism. This multi-functionality eliminates the need for separate dedicated amplifier and filter circuits, reducing overall circuit area while maintaining signal quality
2Power
If an amplifier circuit is added to amplify the desired signal, then signal amplitude is improved, but power consumption increases
Solution Approach 1:
The patent integrates the amplification function into the mixer circuit itself by utilizing bias current flowing through the mixer transistors. This eliminates the need for a separate power-hungry amplifier circuit, reducing power consumption while maintaining adequate signal amplitude for subsequent processing stages
Solution Approach 2:
The mixer circuit performs self-amplification through its inherent transistor operation and bias current configuration. The circuit uses its own operating current to provide the necessary signal amplification without requiring an external dedicated amplifier, thereby reducing overall power consumption
3Adaptability or versatility
If separate amplifier and filter circuits are used, then signal processing capability is improved, but device complexity increases
Solution Approach 1:
The patent merges the image removing mixer circuit and ½-frequency divider circuit into a single integrated unit with shared components and biasing schemes. This integration maintains full signal processing capability including image rejection, frequency conversion, and frequency division, while reducing the number of discrete components and interconnections, thereby simplifying the overall device complexity
Data Source
AI summary
A semiconductor integrated circuit includes a mixer circuit unit having a first single gate mixer configured to receive a first input signal having a first frequency and a second input signal having a second frequency as inputs, a second single gate mixer configured to receive the first input signal and a third input signal of a phase inverted from a phase of the second input signal as inputs, a third single gate mixer configured to receive a fourth input signal of a phase inverted from the phase of the first input signal and the second input signal as inputs, and a fourth single gate mixer configured to receive the third and the fourth input signals as inputs; and a ½-frequency divider unit configured to receive output signals from the first to the fourth single gate mixers as inputs and output a desired signal.