Switching circuit and method
A switching circuit that switches voltage at an output node includes a first switch element configured to enable supplying a first voltage from a first supply node to the output node, a second switch element configured to enable supplying a second voltage from a second supply node to the output node, and a controller. The controller switches the first and the second switch element between a first state and a second state depending on an input voltage. In the first state, the first switch element is in a conducting state and the second switch element is in a non-conducting state, and, in the second state the first switch element is in a non-conducting state and the second switch element is in a conducting state, the switching being performed through an intermediate state in which both the first and the second switch element are in the non-conducting state.
1. A switching circuit for switching a voltage at an output node, the circuit comprising:
a first switch element coupled between a first supply node and the output node, the first supply node being at a first supply voltage;
a second switch element coupled between a second supply node and the output node, the second supply node being at a second supply voltage;
a controller configured to
switch, depending on an input signal, the first and the second switch element between a first state and a second state through an intermediate state, wherein in the first state the first switch element is in a conducting state and the second switch element is in a non-conducting state, and in the second state the first switch element is in a non-conducting state and the second switch element is in a conducting state, and in the intermediate state both the first switch element and the second switch element are in the non-conducting state;
generate a first pulse in response to a falling edge of the input signal and a second pulse in response to a rising edge of the input signal; and
control, by a delay element of the controller, a duration of the first and second pulses by triggering trailing edges of the first and second pulses such that a transition in an output voltage of the output node is preceded by the intermediate state,
wherein the first switch element is configured to switch to the conducting state in response to a leading edge of the first pulse and to the non-conducting state in response to the trailing edge of the first pulse, and
wherein the second switch element is configured to switch to the conducting state in response to a leading edge of the second pulse and to the non-conducting state in response to the trailing edge of the second pulse.
2. The switching circuit as claimed in claim 1 , wherein the first switch element comprises a first transistor and the second switch element comprises a second transistor.
3. The switching circuit as claimed in claim 2 , wherein the first transistor is a first p-type metal oxide silicon, PMOS, transistor, the second transistor is a second n-type metal oxide silicon, NMOS, transistor and the first supply voltage exceeds the second supply voltage.
4. The switching circuit as claimed in claim 3 , the circuit further comprising a complementary NMOS transistor coupled in series with the second NMOS transistor between the second NMOS transistor and the output node, wherein a gate of the first PMOS transistor and a gate of the complementary NMOS transistor are coupled together.
5. An integrated circuit comprising a switching circuit as claimed in claim 1 .
6. A local oscillator circuit for a wireless communication device, comprising a switching circuit as claimed in claim 1 .
7. A wireless communication device comprising a local oscillator circuit as claimed in claim 6 .
8. A method of operating a switching circuit having a first switch element coupled between a first supply node and an output node, the first supply node being at a first supply voltage, and a second switch element coupled between a second supply node and the output node, the second supply node being at a second supply voltage, the method comprising:
dependent on an input signal, switching the switching circuit between a first state and a second state through an intermediate state, wherein in the first state the first switch element is in a conducting state and the second switch element is in a non-conducting state, in the second state the first switch element is in a non-conducting state and the second switch element is in a conducting state, and in the intermediate state both the first switch element and the second switch element are in the non-conducting state;
generating a first pulse in response to a falling edge of the input signal and a second pulse in response to a rising edge of the input signal;
switching the first switch element to the conducting state in response to a leading edge of the first pulse and to the non-conducting state in response to a trailing edge of the first pulse;
switching the second switch element to the conducting state in response to a leading edge of the second pulse and to the non-conducting state in response to a trailing edge of the second pulse; and
controlling a duration of the first and second pulses by triggering the trailing edges of the first and second pulses so that a transition in an output signal of the output node is preceded by the intermediate state.