摘要:
A voltage-to-current circuit utilizes an NMOS-input voltage-to-current (V-I) converter and a PMOS-input V-I converter, with both driving a common gate output stage. Each of the V-I converters includes a transconductance amplifier and a current mirror. The common gate output stage includes two series connected complementary pairs of transistors. One complementary pair drives the output, and the other complementary pair biases the first. The V-I circuit can be utilized as part of a phase detector, which is in turn can be utilized as part of a phase lock loop or a delay lock loop.
摘要:
A phase lock loop circuit including a voltage controlled oscillator and a phase detector having a sampling circuit and a linear voltage-to-current converter to create a control voltage for the voltage controlled oscillator. The phase lock loop circuit comprising a voltage-to-current circuit to influence a voltage on a capacitor, the voltage controlled oscillator responsive to the voltage on the capacitor, and the sampling circuit responsive to the first and second clock signals to generate two voltage values.
摘要:
A differential amplifier has input and output terminals to generate a second signal at the output terminals for a first signal. The amplifier has feedback switches between the output terminals and the input terminals. Offset capacitors are coupled to the differential amplifier at the input terminals and reference voltages via charging switches to provide offsets for the first signal form the reference voltages via input switches.
摘要:
A differential delay cell includes load transistors and a current source transistor biased linearly. The delay control input of the differential delay cell is also the power supply input such that when the power supply voltage changes, the delay in the differential delay cell changes. The resistance presented by the load transistors changes as a function of the power supply voltage, as does the current sourced by the variable current source. The combination of changing resistance and changing current as the power supply voltage changes results in a substantially constant output voltage swing. A ring of differential delay cells is included in a voltage controlled oscillator, which is in turn included in a phase lock loop. The phase lock loop has a wide loop bandwidth and the voltage controlled oscillator has a good power supply rejection ratio.
摘要:
A low jitter external clocking system and method are disclosed. According to one embodiment of the present invention, a differential clock signal is received on a first clock signal line and a second clock signal line. A differential amplifier coupled to the first clock signal line and the second clock signal line amplifies the differential clock signal into a single-ended output clock signal.
摘要:
A differential amplifier is provided, incorporating negative hysteresis by automatic reference voltage adjustment. A delayed output signal is routed to a switch or multiplexer which functions to select one of two reference voltage levels, creating negative hysteresis. The delayed output signal is delayed by a series of inverters, which prevent certain embodiments of the invention from oscillating under some conditions. The two reference voltage levels are selected to be near the respective data signal input high and low signal voltage levels, but far enough from these levels so as not to be adversely affected by noise or other interference.
摘要:
A complementary input self-biased differential amplifier includes gain compensation devices. The gain compensation devices are in parallel with input transistors and are biased by a self-bias node. The gain control devices serve to keep current flowing in load devices when operating at common-mode extremes, thereby limiting the reduction in amplifier output impedance and limiting the corresponding reduction in differential-mode gain at common-mode extremes. The gain control devices also serve to reduce input stage transconductance near the center of the common-mode input voltage swing, thereby reducing differential-mode gain near the center of the swing, and reducing gain variations across the input common-mode range. The differential amplifier can include multiple input legs on either side of an input stage. Multiple legs allow multiple reference voltages to be compared to a data signal. A bidirectional data link utilizes the multiple reference inputs to remove an ambiguity created by the bidirectional data link.
摘要:
A low jitter external clocking system and method are disclosed. According to one embodiment of the present invention, a differential clock signal is received on a first clock signal line and a second clock signal line. A differential amplifier coupled to the first clock signal line and the second clock signal line amplifies the differential clock signal into a single-ended output clock signal.
摘要:
According to some embodiments, a method and apparatus are provided to generate a sine wave via a jitter modulator to modulate a control voltage of a clock source. The jitter modulator is in-situ on a die. The sine wave is received at a clock and data recovery circuit comprising the clock source. The clock and data recovery circuit is in-situ on the die.
摘要:
An adaptive equalizer finite impulse response (FIR) filter for high-speed communication channels with modest complexity, where the filter is iteratively updated during a training sequence by a circuit performing the update: h(t+1)= h(t)+μ[sgn{d(t)}−sgn{z(t)−Kd(t)}]sgn{ x(t)}, where h(t) is the filter vector representing the filter taps of the FIR filter, x(t) is the data vector representing present and past samples of the received data x(t), d(t) is the desired data used for training, z(t) is the output of the FIR filter, μ determines the memory or window size of the adaptation, and K is a scale factor taking into account practical limitations of the communication channel, receiver, and equalizer. Furthermore, a procedure and circuit structure is provided for calibrating the scale factor K.