Wideband Voltage Translator Circuit With Split Frequency Paths
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Solution Overview
Problem
Existing voltage translators in high-speed ICs face challenges with poor low-frequency response, slow speed, high cost, and high power consumption, particularly due to the use of large passive components and slow devices.
Innovation Solution
The solution involves processing high-frequency and low-frequency components of an input signal separately in two parallel stages, using a low-frequency DC-coupled amplifier and a high-frequency AC-coupled amplifier, and then seamlessly merging them at a combining stage without large passive components or slow devices, maintaining the integrity of the frequency response across the complete translator bandwidth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If large series AC-coupling capacitors and large resistors are used to translate signal voltage, then low-frequency response is improved, but circuit area and cost increase
Solution Approach 1:
The voltage translator is divided into two separate processing paths: a low-frequency path using a transconductance amplifier with DC coupling, and a high-frequency path using AC coupling with series capacitors. Each path is optimized for its frequency range, allowing the circuit to achieve good low-frequency response without requiring excessively large passive components across the entire bandwidth.
Solution Approach 2:
The circuit changes its operating parameters based on frequency by using different amplification mechanisms for low and high frequencies. The low-frequency path uses transconductance amplification with DC coupling, while the high-frequency path uses voltage amplification with AC coupling, allowing optimal performance across the full bandwidth without compromising area efficiency.
2Reliability
If large series AC-coupling capacitors are used to translate signal voltage, then low-frequency response is improved, but high-frequency performance deteriorates due to parasitic capacitance
Solution Approach 1:
The frequency spectrum is segmented into low-frequency and high-frequency bands, each processed by a dedicated path. The low-frequency path uses DC coupling to achieve excellent low-frequency response, while the high-frequency path uses AC coupling optimized for high-speed operation, eliminating the trade-off between low-frequency response and high-frequency performance.
Solution Approach 2:
A frequency-dependent switching mechanism or combiner acts as an intermediary that directs different frequency components through appropriate processing paths. This mediator ensures that low-frequency signals are processed with DC coupling while high-frequency signals are processed with AC coupling, maintaining optimal performance across the entire bandwidth.
3Speed
If emitter followers or source followers are used to shift voltages, then speed is improved and large passive components are eliminated, but arbitrary voltage level shifting capability is reduced
Solution Approach 1:
The circuit dynamically selects between different voltage translation mechanisms based on the required output voltage level. For voltage levels requiring arbitrary shifting, the transconductance amplifier path is used which can generate any voltage level through controlled current sources. For speed-critical applications, the AC-coupled path provides fast translation. This dynamic adaptation resolves the contradiction between speed and versatility.
Solution Approach 2:
The voltage translator is designed with multi-functional capability, incorporating both transconductance amplification (for arbitrary voltage level shifting) and AC coupling (for high-speed operation with fixed voltage levels). This universal design allows the same circuit to adapt to different voltage translation requirements, maintaining both versatility and speed performance.
4Area of stationary object
If transconductance amplifier is used to convert input voltage to current signal, then large passive components are eliminated, but translation speed decreases due to slower high-voltage devices or p-type devices
Solution Approach 1:
The translation function is segmented into two parallel paths: one using transconductance amplification for area-efficient voltage level shifting, and another using AC-coupled voltage amplification for high-speed operation. By segmenting the functionality, the circuit achieves both area efficiency and high speed without requiring slow high-voltage devices in the entire signal path.
Solution Approach 2:
The transconductance amplifier path and AC-coupled voltage amplifier path are merged into a unified voltage translator that combines the advantages of both approaches. The output of both paths is combined to provide both area efficiency and high-speed performance, resolving the contradiction between eliminating large passive components and maintaining fast translation speed.
Data Source
AI summary
In embodiments of the present invention, the problems of poor low-frequency response, slow speed, high cost and high power consumption in conventional voltage translators are addressed by processing high frequency and low frequency components of an input signal separately in two parallel stages without the use of large passive components or slow devices. At the output, the processed high frequency and low frequency components are seamlessly merged at a combining stage that maintains the integrity of the frequency response over the complete translator bandwidth.