Abstract:
In conventional analog-to-digital converter (ADC) systems, jitter can be a problem because of delay circuits within the sample signal path. Here, an ADC system is provided with a modified delay locked loop (DLL), namely having a variable delay and a fixed delay. The modification to the delay line of DLL enables the removal of delay circuits from the sample path, improve the overall signal to noise ration (SNR).
Abstract:
A reference generation circuit provided according to an aspect of the present invention generates a reference potential at different levels in the hold phase of different cycles in an input path of a switched capacitor differential amplifier. In an embodiment, for each hold phase, the reference generator provides the reference potential with a magnitude that tracks the magnitude of the input signal applied in a corresponding (preceding) sample phase. In case of a single-ended output, the reference potential generated for each hold phase equals the magnitude of one of the inputs on the differential input path. As a result, the common mode voltage at the input terminals of an operational amplifier contained in the switched capacitor differential amplifier is maintained at a desired level.
Abstract:
A reference generation circuit provided according to an aspect of the present invention generates a reference potential at different levels in the hold phase of different cycles in an input path of a switched capacitor differential amplifier. In an embodiment, for each hold phase, the reference generator provides the reference potential with a magnitude that tracks the magnitude of the input signal applied in a corresponding (preceding) sample phase. In case of a single-ended output, the reference potential generated for each hold phase equals the magnitude of one of the inputs on the differential input path. As a result, the common mode voltage at the input terminals of an operational amplifier contained in the switched capacitor differential amplifier is maintained at a desired level.
Abstract:
A source follower or emitter follower buffer provided according to an aspect of the present invention includes a capacitor connected between the input path and a node formed by the junction of a pair of transistors forming a cascoded current source connected to the output of the buffer. The capacitor passes input signal current directly to a switching load connected to the output of the buffer, and very little signal-dependant current flows through the transistor receiving the input signal. As a result, input-output non-linearity due to signal-dependant modulation (variation) of transconductance of the transistor receiving the input signal is minimized. When incorporated in switched-capacitor analog to digital converters, the buffer facilitates generation of digital codes that represent an input signal more accurately.
Abstract:
A phase locked loop (PLL) circuit includes circuitry for preventing an erroneous condition in charge pump operation. The PLL circuit is modified by adding delay elements for connection between the phase frequency detector and the charge pump. A digital logic circuit is also included to provide the clock signals for the loop filter wherein the clock signals have rising edges corresponding to an earlier occurring rising edge of either of the output signals from the phase-frequency detector.
Abstract:
An offset correction circuit examines a residue signal of a stage of a pipeline analog to digital converter (ADC) to determine whether a parameter which could cause offset error, needs to be adjusted. In an embodiment, the parameter is adjusted until a maximum range of the residue signal equals an expected range. In the described examples, the adjusted parameters include timing offset error (when components of an ADC sample the input signal at different time instances) and a voltage offset error (the threshold voltage at which a sub-ADC in a stage the generated sub-code changes to a next value).
Abstract:
A phase locked loop (PLL) architecture provides voltage controlled oscillator (VCO) gain compensation across process and temperature. A simulator may be used to calculate the control voltages for the maximum and minimum output frequency of the VCO for each combination of the process and temperature corners. The maximum and minimum values of control voltage are then selected from these control voltages. Using a counter, the number of cycles of VCO in some cycles of the PLL input clock are counted in binary form and stored in latches for the extreme control voltages. The difference between them and the corresponding difference for typical process and temperature corner is used to modify the charge pump to change the current delivered to the loop filter. After the charge pump bits have been decided, the input control voltage of the VCO connects to the charge pump output to start the normal operation of the PLL.
Abstract:
A method and system for generating variable frequency cyclic waveforms using pulse width modulation (PWM) to provide adjustable precision frequency and enhanced resolution is disclosed. The technique includes a plurality of sets of duty cycle values, each set corresponding to the desired waveform profile at a given frequency, coupled with a mechanism for applying a selected duty cycle for a variable number of PWM cycles, to achieve an adjustable fine resolution of the waveform frequency.
Abstract:
A method for facilitating the exchange of a stable cryptocurrency collateralized by government-issued debt. First granularity parameters are received through a first wallet interface of a first digital wallet. A first restricted use key is generated based upon the first granularity parameters and provided to an owner of a second digital wallet. A second restricted use key is generated based upon second granularity parameters received through a second wallet interface associated with the second digital wallet. Information from a blockchain wallet is accessed using the second restricted use key wherein the information relates to one or more of an ID classification and risk score of the second wallet owner at a level of detail determined by the second granularity parameters. An indication to proceed with a transaction between the first digital wallet and the second digital wallet may then be received through the first wallet interface.
Abstract:
Traditionally, input source follower buffers for analog-to-digital converters (ADCs) lacked sufficiently high linearity. This was due in part to source follower buffers having to drive external capacitive loads by generally providing a signal current to the capacitive load. Here, a buffer is provided that includes a source follower buffer and other biasing circuitry (which provided the signal current). Thus, the overall linearity of the input circuitry (namely, the input buffer) is improved.