A circuit parameter adjustment circuit for adjusting a circuit parameter (e.g., resistance or capacitance) of a circuit having N network elements connected between two nodes. The circuit parameter adjustment circuit includes N zapping devices and N switching devices coupled between the N zapping devices and the N network elements. When a zapping control signal is low, the N switching devices are directly responsive to respective ones of the N trimming signals for bypassing or not bypassing the respective ones of the N network elements, thereby facilitating testing of the value of the circuit parameter for different combinations of the trimming signals, prior to zapping the zapping devices. Then, after the optimum combination of trimming signals has been selected, the zapping control signal is driven high, whereby the N zapping devices are zapped or unzapped, depending upon the logic level of the respective ones of the N trimming signals.
A voltage clamping circuit for a semiconductor memory device which is capable of rapidly coping with the demand of the user. The voltage clamping circuit includes PMOS transistors connected in series between an external supply voltage terminal and a node on an output line of a DC voltage generator, a control PMOS transistor having a channel connected at both ends thereof respectively to the node on the output line and a node between the second and third ones of the series-connected PMOS transistors, and a pad connected to a control electrode of the control PMOS transistor. The pad is selectively connected to a supply voltage in a first state and to a ground voltage in a second state, thereby controlling a clamping interval of the clamping means to be variable. The first state is a state requiring a longer clamping interval than that of the second state.
In a trimmer method and device, a reference signal of a target circuit is compared with a test signal, and a binary count output is generated according to result of the comparison. Thereafter, according to logic states of bits of the binary count output, electrical conduction through passive components that are coupled to the target circuit and that correspond respectively to the bits of the binary count output are selectively enabled and disabled so as to adjust the reference signal. The above steps are repeated by varying the binary count output until the reference signal approximates the test signal. Thereafter, fuses coupled to the passive components are melted selectively in a single fuse-melting operation so as to maintain the enabled and disabled states of electrical conduction through the passive components in order to set the reference signal to be approximate to the test signal.
A frequency adjustment circuit that maintains a target frequency even when frequency adjustment data of zapping circuit is changed by an external noise is offered. The frequency adjustment circuit includes a reset signal generation circuit, a frequency adjustment data latch circuit that latches and retains the frequency adjustment data ZP1 and ZP2 generated by a first zapping circuit and a second zapping circuit based on a latch clock ZCLK and a latch clock generation circuit that generates the latch clock ZCLK. The reset signal generation circuit generates a periodic reset signal ZRES that is synchronized with a rise of an enable signal EN generated from an interface circuit. The latch clock generation circuit generates the latch clock ZCLK that is synchronized with a fall of the enable signal EN.
An output driver circuit for an integrated circuit is disclosed, where the output driver drives an output terminal with a high logic level having a voltage limited from the power supply voltage of the integrated circuit. The limited voltage is provided by applying a limited output high voltage to an output buffer, such that the drive signal applied to the gate of the pull-up transistor in the output driver is limited by the limited output high voltage applied to the output buffer. A voltage reference and regulator circuit for generating the limited output high voltage is also disclosed, and is based on a current mirror. The sum of the current in the current mirror is controlled by a bias current source, which may be dynamically controlled within the operating cycle or programmed by way of fuses. An offset compensating current source adds current into the reference leg of the current mirror to eliminate the development of an offset voltage in the current mirror, and the limited output high voltage is shifted by the threshold voltage of the pull-up drive transistor by way of a threshold shift circuit.
A method is provided for carrying out a trimming operation on an integrated circuit having a trimming circuit portion which includes memory elements and a modification circuit for modifying the state of the memory elements, at least a first input or supply pin, an output pin, and a second supply pin. According to the method, a single pin is enabled to receive trimming data by biasing the pin to outside its operating range. A clock signal is obtained from a division of the bias potential of the pin, and the logic value of the trimming data is obtained from a different division of the bias potential of the pin. Serial acquisition of the data is enabled in accordance with the clock signal, and the data is transferred to the modification circuit.
