A switched emitter follower circuit is constituted by a transistor in which a base is connected to a signal input terminal, a power voltage is applied to a collector, and an emitter is connected to a signal output terminal, a capacitor in which one end is connected to the collector of the transistor, and the other end is connected to the emitter of the transistor, and a Gilbert-cell type multiplication circuit in which a positive-phase clock output terminal is connected to the emitter of the transistor, a negative-phase clock output terminal is connected to the base of the transistor, and a multiplication result of a differential clock signal and a differential clock signal input from an outside is output to the positive-phase clock output terminal and the negative-phase clock output terminal.

The invention relates to an analog-to-digital converter (1), comprising:

an analog input for receiving an analog signal;
a first time-to-digital converter (7); and a histogram block (10), wherein the first time-to-digital converter (7) scans the analog signal based on a ramp signal, and delivers an output (20, 25) to the histogram block (10), which, based thereon, generates a time-correlated histogram (21, 26, 30).

Certain aspects of the present disclosure generally relate to circuitry and techniques for digital-to-analog conversion. For example, certain aspects provide an apparatus for digital-to-analog conversion. The apparatus generally includes a mixing-mode digital-to-analog converter (DAC), a duty cycle adjustment circuit having an input coupled to an input clock node and having an output coupled to a clock input of the mixing-mode DAC, and a current comparison circuit having inputs coupled to outputs of the mixing-mode DAC and having an output coupled to a control input of the duty cycle adjustment circuit.

A time interleaved analog-to-digital converter (TIADC) is provided. The TIADC converts an input signal into a digital output signal and includes N analog-to-digital converters (ADCs), a clock generation circuit, and a control circuit. The N ADCs receive the input signal and sample the input signal according to N sampling clocks to each generate a digital output code, N being an integer greater than or equal to 2. The clock generation circuit is configured to receive a working clock and a set of control values and to generate the N sampling clocks according to the set of control values and the working clock. The control circuit is configured to periodically generate the set of control values based on a pseudo random number and to output the digital output codes in turn as the digital output signal.

The present invention discloses a method of calibrating time interleaved analog to digital converter comprising: sampling a common input signal, said sampling is performed by an array of sub analog to digital converters, each generating individual digital analog equivalent outputs with sampling time errors, said digital outputs are fed to sampling time error estimation circuitry to calculate a digital output proportional to sampling time error between two consecutive channels, without any restriction on input signal or ADC channel design, said timing skew estimator circuitry composed of generating a delayed output of one of the two consecutive ADC channels, channel first and channel second and subtracting the said delayed output with digital output of the said second channel and producing the first subtracted output and output of said second channel subtracted with said first channel output delayed by sampling delay between the two consecutive channels and producing the second subtracted delayed output, absolute value of the said first subtracted output and said second subtracted delayed output is monitored for peak value of both for a fixed time duration and then subtracted values of the said peak values are the estimation of sampling time error between the said two consecutive channels, same process is repeated to each consecutive ADC channels of the said ADC array.

A system and method for suppressing aperture noise resulting from clock jitter associated with a Nyquist analog-to-digital converter (ADC) using self-referred time measurements are provided. The system comprises of a clock, a delay element, a time subtractor, a time-to-digital converter, a filter element, a first digital subtractor, an integrator, a differentiator, and a multiplier. Each of the delay element, time subtractor, time-to-digital converter, filter element, first digital subtractor, integrator, and multiplier is electrically connected in parallel with the ADC, which allows the clock to generate a clock signal that advances into the system and the ADC in order to isolate and suppress the noise aperture associated with the ADC. As such, the architecture of the system is configured to isolate and suppress aperture noise resulting from clock jitter associated with an analog-to-digital converter (ADC) to allow the output signal of the system be independent of the aperture noise.

A controlled switch having N inputs and a single output (N≥2) is switchable between N states. In each state a respective one of the inputs is connected to the single output. There are N sources of sub-streams of analog samples, each sub-stream composed of pairs of adjacent analog samples. Each source is coupled to a respective one of the inputs. In operation, the controlled switch is controlled by a control signal to switch between the N states. While the controlled switch is in any one of the states, a data transition occurs between two adjacent analog samples in the sub-stream whose source is coupled to the input that is connected to the single output. The single output yields a high-bandwidth analog signal. Any pair of adjacent analog samples in any one of the sub-streams substantially determines a corresponding pair of adjacent analog samples in the high-bandwidth analog signal.

In described examples, a phase locked loop (PLL) has a first phase detector cell (PD) that has a gain polarity. The first PD cell has a phase error output and inputs coupled to a reference frequency signal and a feedback signal. A second PD cell has an opposite gain polarity. The second PD cell has a phase error output and inputs coupled to the reference frequency signal and the feedback signal. A loop filter has a feedforward path and a (lossy) integrating path coupled to an output of the filter. The feedforward path has a third PD cell that has phase error output AC-coupled to the filter output. The integrating path includes an opamp that has an inverting input coupled to the first PD cell phase error output and a non-inverting input coupled to the second PD cell phase error output.

An analog-to-digital conversion circuit includes; a first analog-to-digital converter (ADC), a second ADC and a third ADC collectively configured to perform conversion operations according to a time-interleaving technique, and a timing calibration circuit configured to calculate correlation values and determine differences between the correlation values using first samples generated by the first ADC, second samples generated by the second ADC, and third samples generated by the third ADC during sampling periods, wherein the timing calibration circuit is further configured to control a phase of a clock signal applied to the second ADC in response to a change in absolute value related to the differences generated during the sampling periods.

A circuit includes, in part, a first transistor receiving a first clock signal at its gate, a second transistor receiving a second clock signal at its gate, a first impedance coupled to the drain terminal of the first transistor, a second impedance coupled to the drain terminal of the second transistor, a current source coupled to the source terminals of the first and second transistors, a third transistor receiving a third clock signal at its gate, a fourth transistor receiving a fourth clock signal at its gate, a fifth transistor coupling the drain terminal of the third transistor to the second impedance in response to a first control signal, a sixth transistor coupling the drain terminal of the fourth transistor to the second impedance in response to a second control signal, and a first variable current source coupled to the source terminals of the third and fourth transistors.