Apparatus and method for driving laser diode arrays with high-power pulsed currents using low-side linear drive with laser diode array protection and power efficiency monitoring and adjustment
First Claim
1. A multi-stage laser drive circuit configured to draw current from a variable common potential source, comprising:
- a current node;
a first power amplifier (PA) light-emitting array in electrical communication between a storage capacitor and the current node through a digitally controllable ON/OFF switch, the storage capacitor being charged by the variable common potential source through a charge control circuit;
a first low side linear current sink in electrical communication with the current node, the first low side linear current sink being configured to draw a first current (I1) from the storage capacitor through the ON/OFF switch, through the current node;
a second low side linear current sink in electrical communication with the current node and in a parallel arrangement with respect to the first low side linear current sink, the second low side linear current sink being configured to draw a second current (I2) from the storage capacitor through the ON/OFF switch, through the current node;
a second master oscillator (MO) light-emitting array in electrical communication between the current node and the first low side linear current sink, wherein current through the first light-emitting array is the sum of the first and second currents in parallel, wherein output light from the first PA light-emitting array is used to pump a first PA laser gain medium;
wherein output light from the second MO light-emitting array is used to pump a second MO laser gain medium;
a trickle current circuit located between the common potential source and an anode of a laser diode at a top of the first PA light-emitting array for driving a low-value trickle current through the first and second light emitting arrays and through a fixed shunt resistor in parallel with the first low side linear current sink;
a sense circuit for sensing a voltage indicative of a magnitude of the trickle current at an input of the first low side linear current sink and generating a signal indicative of the voltage; and
a digital controller for generating a switch control signal to control the ON/OFF switch such that the first and second currents are prevented from flowing if the signal indicative of the trickle voltage indicates that the trickle voltage is outside a voltage range to indicate a malfunction, the malfunction being one of an open circuit and a short circuit, indicated by the trickle voltage;
wherein the first low side linear current sink contains a pass element and a second sense circuit, the second sense circuit sensing a voltage across the pass element and generating a signal indicative of the voltage across the pass element, the digital controller monitoring the voltage via an analog-to-digital converter (ADC) and generating a digital control signal to vary an output of the common potential source to control the voltage across the pass element to an absolute minimum during the current pulse ON time, while maintaining pass element linearity.
1 Assignment
0 Petitions
Accused Products
Abstract
A multi-stage laser drive circuit includes a variable common potential source, a PA light-emitting array between a storage capacitor and a current node, first and second low-side linear current sinks in electrical communication with the current node, and a second master oscillator (MO) light-emitting array in electrical communication between the current node and the first low side linear current sink. A trickle current circuit drives a low-value trickle current through the arrays, and a sense circuit senses the trickle current. Also, the headroom voltage across a pass element in the first low-side linear constant current sink is monitored and adjusted for maximum efficiency.
-
Citations
10 Claims
-
1. A multi-stage laser drive circuit configured to draw current from a variable common potential source, comprising:
-
a current node; a first power amplifier (PA) light-emitting array in electrical communication between a storage capacitor and the current node through a digitally controllable ON/OFF switch, the storage capacitor being charged by the variable common potential source through a charge control circuit; a first low side linear current sink in electrical communication with the current node, the first low side linear current sink being configured to draw a first current (I1) from the storage capacitor through the ON/OFF switch, through the current node; a second low side linear current sink in electrical communication with the current node and in a parallel arrangement with respect to the first low side linear current sink, the second low side linear current sink being configured to draw a second current (I2) from the storage capacitor through the ON/OFF switch, through the current node; a second master oscillator (MO) light-emitting array in electrical communication between the current node and the first low side linear current sink, wherein current through the first light-emitting array is the sum of the first and second currents in parallel, wherein output light from the first PA light-emitting array is used to pump a first PA laser gain medium;
wherein output light from the second MO light-emitting array is used to pump a second MO laser gain medium;a trickle current circuit located between the common potential source and an anode of a laser diode at a top of the first PA light-emitting array for driving a low-value trickle current through the first and second light emitting arrays and through a fixed shunt resistor in parallel with the first low side linear current sink; a sense circuit for sensing a voltage indicative of a magnitude of the trickle current at an input of the first low side linear current sink and generating a signal indicative of the voltage; and a digital controller for generating a switch control signal to control the ON/OFF switch such that the first and second currents are prevented from flowing if the signal indicative of the trickle voltage indicates that the trickle voltage is outside a voltage range to indicate a malfunction, the malfunction being one of an open circuit and a short circuit, indicated by the trickle voltage; wherein the first low side linear current sink contains a pass element and a second sense circuit, the second sense circuit sensing a voltage across the pass element and generating a signal indicative of the voltage across the pass element, the digital controller monitoring the voltage via an analog-to-digital converter (ADC) and generating a digital control signal to vary an output of the common potential source to control the voltage across the pass element to an absolute minimum during the current pulse ON time, while maintaining pass element linearity. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
-
Specification