JP2532372B2 - High speed scanning charge transfer device - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a charge transfer device, and more particularly to a scan pulse generator that can be used in a high speed scan charge transfer device.

2. Description of the Related Art In recent years, high-speed scanning pulse generators are in great demand for transfer in high-speed scanning charge transfer devices, and transfer speed control is possible.
And high speed is desired. When generating high-speed scanning pulses, inverter circuits have been connected vertically,
A so-called self-scanning pulse generation circuit is often used.

Hereinafter, the conventional self-scanning pulse generator as described above will be described with reference to the drawings.

FIG. 2 is a circuit diagram of a conventional self-scanning pulse generator. In the figure, (4-1) is an inverter, (4-2) is an input terminal for applying an input pulse, (4)
-3) is an output terminal of the first stage, and (4-4) is an output terminal of the second stage.

FIG. 3 shows input / output waveforms when the circuit of FIG. 2 is operated. In the figure, the vertical axis represents voltage and the horizontal axis represents time. (5-a) is a pulse waveform of the input terminal (4-2), (5-b) is a pulse waveform of the output terminal (4-3), (5-c) is a pulse waveform of the output terminal (4-4). Is. (T _D ) is the pulse delay time.

The operation of the self-scanning pulse generator configured as described above will be described below.

First, when the pulse waveform (5-a) is input to the input terminal (4-2), the pulse waveform (5-b) is output to the output terminal (4-3) after passing through the inverter (4-1) in two stages. It At this time, the delay time (t _D ) of the pulse is
1) The delay time is two stages. Further, the pulse passes through the next inverter (4-1) in two stages, and the output terminal (4-4)
The pulse waveform (5-c) is output (the pulse delay time (t _D ) at this time is also two stages of the inverter (4-1)), and the pulses are sequentially scanned.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention However, in the above-described conventional configuration, the pulse interval, that is, the pulse delay time (t _D ) is determined by the inverter
The inverter (4-1) is determined by the delay time characteristic of 1).
It has a drawback that the pulse interval cannot be made shorter than the delay time. In addition, the inverter (4-1)
Always turns on either even or odd number
Therefore, this scanning pulse generator has a drawback that power consumption increases.

In view of the above-mentioned drawbacks, the present invention provides a high-speed scanning charge transfer device capable of arbitrarily changing the pulse interval, that is, the pulse delay time (t _D ) without being limited by the delay time of the inverter and capable of driving with low power consumption. It is provided.

Means for Solving the Problems In order to solve the above problems, the high-speed scanning charge transfer device according to the present invention uses a plurality of reference voltage points as the scanning pulse generating means coupled to the charge transfer means of the charge transfer device. A unit circuit is composed of the reference voltage generating section and the pulse generating section, and the pulse generating section has a control terminal connected to one reference voltage point of the reference voltage generating section and an input terminal connected to a pulse input terminal. A connected transistor, a capacitor connected between the output terminal of this transistor and a ground point, and an inverter connected to the output terminal of the transistor, and a plurality of the unit circuits are connected in cascade, The input terminals of the respective transistors of the pulse generator are commonly connected to the pulse input terminal, and the reference voltage point of the reference voltage generator is provided for each unit circuit. The voltages are sequentially set with a predetermined voltage difference.

Action With this configuration, the pulse timing of the charge transfer can be changed arbitrarily, and thus a high-speed scanning charge transfer device can be provided. In addition, unlike the inverter method used in the conventional self-scanning pulse generator, neither the odd-numbered or the even-numbered are all turned on. Driving with low power consumption is possible.

Embodiments Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a schematic diagram of a scanning pulse generator used in a high speed scanning charge transfer device according to an embodiment of the present invention. In the figure, (E) is a reference voltage generating power source as a reference voltage generating unit, and (R) is a voltage dividing resistor for obtaining the reference voltage. (1) is an input pulse applying terminal as an input terminal. Also, (2) is a MOSFFT, (3) is a capacitor,
(4) is an inverter that detects and inverts the potential of the capacitor (3), and these MOSFET (2), capacitor (3), and inverter (4) form a pulse generator (5). Further, the reference voltage generating power source (E) and the pulse generating section (5) constitute a unit circuit (7), and the respective unit circuits (7) are connected to each other in a time series connection.

(V _G1 )-(V _G3 ) is the gate voltage of each MOSFET (2), and V _G1 = (3R / 4R) ・ E = (3/4) ・_EVG2 = (2R / 4R) ・ E = (1/2) ・ EV _G3 = (R / 4R) ・ E = (1/4) ・ E. Further, (I _D1 ) to (I _D3 ) are drain currents flowing into the respective capacitors (3), and the drain currents (I _D1 ) to (I _D3 ) are generally represented by the following equations,
Each depends on each gate voltage (V _G1 ) to (V _G3 ).

Where (β) is the gain coefficient of the transistor, (V _G ) is the gate voltage, (V _T ) is the threshold voltage of the transistor,
(V _D ) is the drain voltage.

The operation of the scan pulse generator for the high speed scan charge transfer device configured as described above will be described below.
First, when high is applied to the input pulse application terminal (1), MO
Charging of the capacitor (3) is started by the drain current ( _ID ) through the SFET (2). Drain current at this time (I _D) is determined by the gate voltage (V _G). Eventually, the potential of each capacitor (3) reaches the threshold voltage (V _T ) of the inverter (4). The time (T _O ) at this time is calculated by the following equation.

From equation (i) and equation (ii), Becomes

Therefore, in each inverter (4), the timing of successive inversion is shifted due to the difference in drain current (I _D ),
It can be output as a scanning pulse.

Although the charging time of the capacitor (3) is controlled by the drain current (I _D ) of the MOSFET (2) in the above embodiment, any device that can control the current by the voltage may be used. For example, a bipolar transistor can be used.

As described above, according to the high-speed scanning charge transfer device of the present invention, it is possible to arbitrarily change the pulse timing of each output pulse output from the output terminal of the inverter and to drive with low power consumption. It can be done, and its practical effect is great.

[Brief description of drawings]

FIG. 1 is a schematic (circuit) diagram of a scanning pulse generator in an embodiment of the present invention, FIG. 2 is a circuit diagram of a conventional scanning pulse generator, and FIG. 3 is a pulse at each terminal of a conventional scanning pulse generator. It is a waveform diagram showing a waveform. (E) ... power supply for generating reference voltage (reference voltage generating section),
(1) ... Input pulse application terminal (input terminal), (5) ...
… Pulse generator, (7) …… Unit circuit.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-55-154819 (JP, A) JP-A-60-113521 (JP, A) Actual development 57-177299 (JP, U)

Claims (2)

(57) [Claims] 1. A unit circuit is constituted by a reference voltage generating section having a plurality of reference voltage points and a pulse generating section as a scanning pulse generating means coupled to a charge transfer means of a charge transfer device, and the pulse generating section is A transistor having a control terminal connected to one reference voltage point of the reference voltage generator and an input terminal connected to a pulse input terminal, and a capacitor connected between the output terminal of the transistor and a ground point. And an inverter connected to the output terminal of the transistor, the plurality of unit circuits are cascaded, the input terminal of each transistor of each pulse generation unit is commonly connected to the pulse input terminal, High-speed scanning charge transfer characterized in that the reference voltage points of the reference voltage generator are sequentially set with a predetermined voltage difference for each unit circuit. Location. 2. The high speed scanning charge transfer device according to claim 1, wherein the transistor is one of a MOSFET and a bipolar transistor.