CN113472344A

CN113472344A - Novel frequency divider

Info

Publication number: CN113472344A
Application number: CN202110924386.5A
Authority: CN
Inventors: 陆熙良; 曾奕恩; 李拥平; 孙中亮; 曾奕棻
Original assignee: Beijing Beidou Huada Technology Co ltd
Current assignee: Beijing Beidou Huada Technology Co ltd
Priority date: 2021-08-12
Filing date: 2021-08-12
Publication date: 2021-10-01

Abstract

The embodiment of the invention discloses a novel frequency divider, which comprises 4 three-input NOR gates with the same specification, wherein the 4 three-input NOR gates are connected in a ring shape, and the output end of each three-input NOR gate is connected with one input end of the next adjacent three-input NOR gate. The invention only needs one level of logic gate, and can effectively save power consumption and area compared with the two-level method of synthesizing 25% duty ratio output by using a frequency divider and a NAND gate or a NOR gate.

Description

Novel frequency divider

Technical Field

The invention relates to the technical field of integrated circuits, in particular to a novel frequency divider.

Background

Due to the popularity of current-mode passive mixers, a signal with a 25% duty cycle is generally required for local oscillator signals. The most common practice for generating such local oscillation signals is that in 2010, the Journal of Solid-State Circuit "Analysis and optimization of direct-conversion receivers with 25% duty-cycle current-drive mixers", and a NAND gate (NOR gate is also possible) is followed by a frequency divider, as shown in fig. 1. The technical scheme has the defects of large power consumption and large area.

Disclosure of Invention

The technical problem to be solved by the embodiments of the present invention is to provide a novel frequency divider to reduce power consumption and area.

In order to solve the above technical problem, an embodiment of the present invention provides a novel frequency divider, including 4 three-input nor gates with the same specification, where the 4 three-input nor gates are connected in a ring, and an output end of each three-input nor gate is connected to an input end of a next adjacent three-input nor gate.

Further, the three-input nor gate includes 2 MOS connected in parallel.

Correspondingly, the embodiment of the invention also provides a novel frequency divider, which comprises 4 three-input NAND gates with the same specification, wherein the 4 three-input NAND gates are connected in a ring shape, and the output end of each three-input NAND gate is connected with one input end of the next adjacent three-input NAND gate.

Further, the three-input nand gate comprises 2 MOS connected in parallel.

The invention has the beneficial effects that: the invention only needs one level of logic gate, and can effectively save power consumption and area compared with the two-level method of synthesizing 25% duty ratio output by using a frequency divider and a NAND gate (or a NOR gate).

Drawings

Fig. 1 is a schematic diagram of a prior art frequency divider.

Fig. 2 is a structural diagram of the novel frequency divider of embodiment 1 of the present invention.

Fig. 3 is a timing diagram of the logic levels of the input and output signals of the novel frequency divider according to embodiment 1 of the present invention.

Fig. 4 is a structural diagram of the novel frequency divider of embodiment 2 of the present invention.

Fig. 5 is a schematic diagram of MOS structures of a three-input nor gate and a three-input nand gate according to an embodiment of the invention.

Detailed Description

It should be noted that the embodiments and features of the embodiments in the present application can be combined with each other without conflict, and the present invention is further described in detail with reference to the drawings and specific embodiments.

Example 1: referring to fig. 2, the novel frequency divider of the embodiment of the invention includes 4 three-input nor gates with the same specification. The 4 three-input NOR gates are connected in a ring shape, and the output end of each three-input NOR gate is connected with one input end of the next adjacent three-input NOR gate. The novel frequency divider of the embodiment of the invention directly generates four different phase signals with the frequency of one half of the input clock and the duty ratio of 25% by utilizing the clock signal provided by the outside.

The present invention uses four identical three-input NOR gates (3-input NOR gate) connected in a ring shape, and directly generates four different phase signals with frequency of one half of the input clock and duty ratio of 25% by using the clock signal provided from the outside. The overall circuit architecture is shown in fig. 2. The four NORs in the ring structure are each controlled by an input clock and the output signals of the first two-stage NORs, wherein the polarities of the input clocks are exchanged between any two adjacent (generating adjacent phases) NORs.

The truth table of the three-input nor gate is shown in table 1:

by alternating the polarity of the input clock and the output signals of the two previous stages of NOR, the structure can ensure that only one NOR output is 1 at the same time, and the pulse width is equal to the input clock signal, which is equivalent to an output signal with 25% duty ratio and half of the input clock frequency. The timing diagram of the logic levels of each input and output signal is shown in FIG. 3.

The three-input NOR gate can realize a phase inverter circuit by using a CMOS, PMOS and NMOS tubes are connected in a full complementary mode, grid electrodes are connected to be used as input three PMOS series, three NMOS series are connected, drain electrodes of the PMOS and the NMOS are connected to be used as output, a source electrode of the PMOS tube is connected with a substrate to form a high level, and a source electrode of the NMOS tube is connected with the substrate to form a low level.

As an embodiment, the three-input nor gate includes 2 MOS connected in parallel.

Example 2: according to the morgan law, this structure can also be implemented by a three-input NAND gate (3-input NAND gate), and referring to fig. 4, the novel frequency divider of the embodiment of the present invention includes 4 three-input NAND gates with the same specification. The 4 three-input NAND gates are connected in a ring shape, and the output end of each three-input NAND gate is connected with one input end of the next adjacent three-input NAND gate. The novel frequency divider of the embodiment of the invention directly generates four different phase signals with the frequency of one half of the input clock and the duty ratio of 75% by utilizing the clock signal provided by the outside, and obtains the different phase signals with the duty ratios of 25% by adding the inverter of the odd level.

As an embodiment, the three-input nand gate includes 2 MOS connected in parallel.

As shown in fig. 5, since there is necessarily one output signal of the first two stages of NORs, and the input clock signal is also 1 when the logic value is 1, one MOS in the three-input NAND gate or the three-input NOR gate (NOR or NAND) of the present invention can be omitted without affecting the normal operation thereof, thereby further reducing the layout area and the parasitic and power consumption corresponding thereto.

The difference between the NAND (NAND) and NOR (NOR) implementations of the present invention is two-fold:

1. the NAND architecture requires four extra inverters to generate a 25% duty cycle signal, so the power consumption may be slightly larger than the NOR architecture, but the signal slew rate (slew rate) is also higher.

2. Since the current driving capability of the PMOS with the same size in the CMOS process is usually only about one half of that of the NMOS with the same size, and the PMOS series structure of NOR makes the current driving capability of the PMOS worse, a larger PMOS size is required to maintain the current driving force close to that of the NMOS; the PMOS and NMOS device size ratio of the NAND structure can be relatively close, and the physical circuit layout and parasitic control optimization are relatively easy. In addition, because one output signal of the first two-stage NOR is required, and the input clock signal is also 1 when the logic value is 1, one parallel MOS in the NOR or the NAND can be omitted without influencing the normal operation, thereby further reducing the parasitic and power consumption of the layout area and the corresponding power consumption. The MOS structure and simplification of NOR and NAND are shown in FIG. 5.

The actual simulation results of the above two architectures are shown in table 2:

the transistors of the logic gate of the invention may be of HBT, MOS, pHEMT type, but it is not limited to these types, and elements with the same function simply replaced may be used.

Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes, modifications, substitutions and alterations can be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.

Claims

1. The novel frequency divider is characterized by comprising 4 three-input NOR gates with the same specification, wherein the 4 three-input NOR gates are connected in a ring mode, and the output end of each three-input NOR gate is connected with one input end of the next adjacent three-input NOR gate.

2. The novel frequency divider of claim 1, wherein the three-input nor gate comprises 2 MOS in parallel.

3. The novel frequency divider is characterized by comprising 4 three-input NAND gates with the same specification, wherein the 4 three-input NAND gates are connected in an annular mode, and the output end of each three-input NAND gate is connected with one input end of the next adjacent three-input NAND gate.

4. The novel frequency divider of claim 3, wherein the three-input NAND gate comprises 2 MOS's in parallel.