CTLE Gain Control Circuit With Equal-Step Programmable Peaking
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Solution Overview
Problem
Conventional high-speed continuous-time linear equalizers (CTLEs) face limitations in programmable gain adjustment, requiring additional stages due to parasitic components and restricted programmable peaking gain, which hinders their ability to effectively manage signal gain across various communication channels.
Innovation Solution
A gain control circuit is introduced, featuring diode-connected transistors and a current digital-to-analog converter that generates currents based on an N-bit input code, allowing precise control of signal gain by adjusting the ratio of these currents, thereby overcoming the limitations of conventional CTLEs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If conventional CTLE varies DC gain to change equalizer gain, then equalizer gain is adjusted, but additional gain stage is required and device complexity increases
Solution Approach 1:
The patent combines the DC gain control and peaking gain control into a single integrated gain control circuit. The first and second diode-connected transistors are controlled by a unified current digital-to-analog converter that generates both control signals simultaneously, eliminating the need for separate gain stages and reducing overall device complexity while maintaining full programmable gain adjustment capability.
Solution Approach 2:
The gain control circuit is designed to perform multiple functions: it controls both the DC gain and the peaking gain of the CTLE through a single circuit architecture. The current digital-to-analog converter generates multiple control signals that simultaneously adjust different gain parameters, making the circuit universal and eliminating the need for additional dedicated gain stages.
2Adaptability or versatility
If conventional CTLE uses switch parasitic components for gain control, then gain adjustment is limited, but programmable peaking gain is restricted
Solution Approach 1:
The patent changes the control parameter from voltage-based switch control to current-based transistor control. By using a current digital-to-analog converter to generate control currents that are converted to voltages through diode-connected transistors, the system achieves wider programmable peaking gain range and finer resolution without being constrained by switch parasitic components. The exponential current-voltage relationship of the diode-connected transistors enables precise gain control over a broader range.
3Ease of operation
If additional gain stage is added to adjust DC gain, then DC gain control is achieved, but device complexity and power consumption increase
Solution Approach 1:
The patent merges the DC gain control function into the existing gain control circuit by using the same current digital-to-analog converter and diode-connected transistors to generate both DC gain control signals and peaking gain control signals. This integration eliminates the need for an additional separate gain stage, thereby reducing power consumption while maintaining full DC gain adjustability.
Data Source
AI summary
Embodiments of a gain control circuit and a wideband communication circuit that uses the gain control circuit are disclosed. In an embodiment, gain control circuit includes first and second output terminals to output gain control signals and first and second diode-connected transistors connected between a supply voltage and the first and second output terminals, which are connected to input terminals of a communication component circuit with a plurality of input transistors. The gain control circuit further includes a current digital-to-analog converter connected to the diode-connected transistors to generate first and second currents for the diode-connected transistors based on an N-bit input code, wherein a ratio of the first and second currents sets voltages of the gain control signals that are output from the gain control circuit to the communication component circuit to control signal gain provided by the communication component circuit.