Provided is a reference voltage circuit including a Zener diode having a cathode connected to a current source via a first node, and an anode connected to a ground point; a first resistor having one end connected to the first node; a second resistor having one end connected to another end of the first resistor; a first diode having an anode connected to another end of the second resistor via a second node, and a cathode connected to the ground point; and a current control circuit configured to generate a control current corresponding to an anode voltage of the first diode so that the current source supplies a reference current corresponding to the control current to the first diode.

A voltage pre-regulator can receive a variable voltage in a middle voltage range (e.g., dozens of volts) and provide a regulated voltage in a safe operating region of a low voltage device. The use of the voltage pre-regulator can allow circuits to use low voltage devices to perform additional regulation/conversion without fear of damage. The voltage pre-regulator disclosed herein can perform the voltage reduction and regulation functions of pre-regulation with commonly used transistor types because the disclosed circuits and method use a bias circuit. The bias circuit uses positive feedback so that no additional start-up circuitry is required. The positive feedback is controlled by negative feedback so that the pre-regulator is able to provide a regulated voltage that is stable over a range of input voltages and temperatures.

A first current mirror circuit is provided between a first transistor and a power supply line to return a current that flows to the first transistor. A second current mirror circuit returns an output current from the first current mirror circuit, and generates a starting current. An inverter has an input connected to a node, and an output connected to a control terminal of the first transistor. A first current source generates a first current when a power supply voltage has exceeded a first threshold value. A third current mirror circuit draws a current proportional to the first current from an input side of the second current mirror circuit. A second current source supplies a second current to the node when the power supply voltage has exceeded a second threshold value.

A low-power CMOS reference voltage generating with enhanced power supply rejection ratio (PSRR) and fast start-up time is disclosed. The reference voltage generating is generated by the stacked diode-connected MOS transistors (SDMT) architecture to reduce the dependence on process, voltage and temperature. The self-biased and capacitor coupled architecture can shorten the start-up time without increasing power consumption and improve the bandwidth of the power supply rejection ratio. This design is implemented using a CMOS process, which can achieve stabilization time of 0.2 ms. Under the same power consumption, this design is 274 times better than a design without a start-up time enhancement. The power supply rejection ratio measured at 100 Hz is −73.5 dB. In the temperature range of −40 to 130° C., the average temperature coefficient is 62 ppm/° C.

A current mirror circuit includes a current input circuit, a current output circuit and a negative feedback circuit. A first terminal of the current input circuit receives input current, a second terminal of the current input circuit is coupled to a second terminal of the current output circuit, a first terminal of the current output circuit outputs mirror current. The negative feedback circuit includes a first transistor and a second transistor, a first terminal of the first transistor is coupled to a third terminal of the current input circuit, a second terminal of the first transistor is coupled to a second terminal of the second transistor. The first terminal of the second transistor is coupled to the third terminal of the current output circuit, the third terminal of the second transistor is grounded. The current mirror circuit improves the output impedance.

The present invention discloses a reference circuit with temperature compensation, which is characterized in that a current output circuit is designed to receive a reference voltage from a bias voltage generation circuit, generate two reference currents with opposite temperature variation characteristics, and then merge them into a compensated current with temperature compensation. In addition, a voltage output circuit is designed to receive a reference voltage from a bias voltage generation circuit, which includes several field-effect transistors operating in saturation regions, and a precision voltage increases with threshold voltages of the field-effect transistors to compensate for the temperature variation. Resistors can be incorporated or sizes of the field effect transistors can be changed to adjust the output current, output voltage or the temperature variation characteristics.

An example apparatus can be a low voltage bandgap circuit that includes a bandgap core portion. The bandgap core portion includes an operational amplifier (op-amp). The op-amp includes a PMOS input and an NMOS input. Further, the op-amp is a folded cascode op-amp. The bandgap core portion further includes a first diode coupled to the op-amp. The bandgap core portion further includes a second diode coupled to the op-amp through a resistor.

Systems and methods are provided for generating a temperature compensated reference voltage. A temperature compensation circuit may include a proportional-to-absolute temperature (PTAT) circuit, and a complementary-to-absolute temperature (CTAT) circuit, with the PTAT circuit and the CTAT circuit including at least one common metal-oxide-semiconductor field-effect transistor (MOSFET) and being configured to collectively generate a reference voltage in response to a regulated current input. The PTAT circuit may be configured to produce an increase in magnitude of the reference voltage with an increase of temperature, and the CTAT circuit may be configured to generated a decrease in magnitude of the reference voltage with the increase of temperature, wherein the increase in magnitude of the reference voltage produced by the PTAT circuit is at least partially offset by the decrease in magnitude of the reference voltage produced by the CTAT circuit.

An offset compensation device includes a first bias module and a second bias module. The first bias module includes a plurality of first current control circuits and a plurality of second current control circuits coupled in parallel. Each of the first current control circuits generates a first reference current, and each of the second current control circuits generates a second reference current. The second bias module includes a plurality of third current control circuits and a plurality of fourth current control circuits coupled in parallel. Each of the third current control circuits generates a third reference current, and each of the fourth current control circuits generates a fourth reference current. The second reference current is greater than the first reference current, and the fourth reference current is greater than the third reference current.

In certain aspects, a clamp circuit includes a first current mirror having a first branch and a second branch, wherein the first current mirror is configured to mirror a current flowing through the first branch of the first current mirror to the second branch of the first current mirror. The clamp circuit also includes a second current mirror having a first branch and a second branch, wherein the second current mirror is configured to mirror a current flowing through the first branch of the second current mirror to the second branch of the second current mirror. The first branch of the first current mirror is coupled in series with the second branch of the second current mirror, and the second branch of the first current mirror is coupled in series with the first branch of the second current mirror.