Biphase clock

N

Niall 84

Guest
Hello,
I am doing a project in college, Design of Switched capacitor filters
for a PCM Speech CODEC.

I am having trouble with the design of a BIPHASE clock which is meant
to drive the switches.

Can anyone give me any tips or point me towards a website which might
be able to help?

Thanks

Niall
 
I read in sci.electronics.design that Niall 84 <niall_heavey@yahoo.com>
wrote (in <1111586028.193930.297970@g14g2000cwa.googlegroups.com>) about
'Biphase clock', on Wed, 23 Mar 2005:
Hello,
I am doing a project in college, Design of Switched capacitor filters
for a PCM Speech CODEC.

I am having trouble with the design of a BIPHASE clock which is meant
to drive the switches.
Click to expand...
Well, what 'trouble' are you having?
Can anyone give me any tips
Click to expand...
Not without knowing what your problem is, in some detail.

or point me towards a website which might
be able to help?

You'll get much better advice here than on most web sites, unless it's
Click to expand...
one recommended from here.

You may also get a free training course in Gratuitous Abuse 101, but,
hey, it's all part of Life's Rich Pageant.
--
Regards, John Woodgate, OOO - Own Opinions Only.
There are two sides to every question, except
'What is a Moebius strip?'
http://www.jmwa.demon.co.uk Also see http://www.isce.org.uk
 
"Niall 84" <niall_heavey@yahoo.com> wrote in message
news:1111586028.193930.297970@g14g2000cwa.googlegroups.com...
Hello,
I am doing a project in college, Design of Switched capacitor filters
for a PCM Speech CODEC.

I am having trouble with the design of a BIPHASE clock which is meant
to drive the switches.

Can anyone give me any tips or point me towards a website which might
be able to help?

Thanks

Niall
Click to expand...
Use a crystal oscillator running at 4X speed and divide the output in two D
flip-flops connected to generate quadrature signals. That is, the Q outputs
of the two flops should be 00, 10, 11, 01 and 00, etc. This will be two
square waves in quadrature which is what a biphase clock is. Use a state
diagram to figure how to connect the flops. Hint, Q1 to D2, Qbar2 to D1.
Bob
 
Bob Eldred wrote:
"Niall 84" <niall_heavey@yahoo.com> wrote in message
news:1111586028.193930.297970@g14g2000cwa.googlegroups.com...
Hello,
I am doing a project in college, Design of Switched capacitor
filters
for a PCM Speech CODEC.

I am having trouble with the design of a BIPHASE clock which is
meant
to drive the switches.

Can anyone give me any tips or point me towards a website which
might
be able to help?

Thanks

Niall

Use a crystal oscillator running at 4X speed and divide the output in
two D
flip-flops connected to generate quadrature signals. That is, the Q
outputs
of the two flops should be 00, 10, 11, 01 and 00, etc. This will be
two
square waves in quadrature which is what a biphase clock is. Use a
state
diagram to figure how to connect the flops. Hint, Q1 to D2, Qbar2 to
D1.
Bob
I think he means non overlapping, eg ÷2,and the clock with Q, /Q
Click to expand...
 
<peg@slingshot.co.nz> wrote in message
news:1111631007.045395.31650@f14g2000cwb.googlegroups.com...

Bob Eldred wrote:
"Niall 84" <niall_heavey@yahoo.com> wrote in message
news:1111586028.193930.297970@g14g2000cwa.googlegroups.com...
Hello,
I am doing a project in college, Design of Switched capacitor
filters
for a PCM Speech CODEC.

I am having trouble with the design of a BIPHASE clock which is
meant
to drive the switches.

Can anyone give me any tips or point me towards a website which
might
be able to help?

Thanks

Niall

Use a crystal oscillator running at 4X speed and divide the output in
two D
flip-flops connected to generate quadrature signals. That is, the Q
outputs
of the two flops should be 00, 10, 11, 01 and 00, etc. This will be
two
square waves in quadrature which is what a biphase clock is. Use a
state
diagram to figure how to connect the flops. Hint, Q1 to D2, Qbar2 to
D1.
Bob
Click to expand...
I think he means non overlapping, eg ÷2,and the clock with Q, /Q

Yes, well I thought of that but figured he couldn't have trouble with a
simple 180 deg wave train could he? If that's the case, he can use a single
D flop with a 2X clock. D to Qbar.
Bob
 
"Niall 84" <niall_heavey@yahoo.com> schreef in bericht
news:1111586028.193930.297970@g14g2000cwa.googlegroups.com...
Hello,
I am doing a project in college, Design of Switched capacitor filters
for a PCM Speech CODEC.

I am having trouble with the design of a BIPHASE clock which is meant
to drive the switches.

Can anyone give me any tips or point me towards a website which might
be able to help?

Thanks

Niall
Click to expand...
Niall,

If your targets are edge triggered, you only need a D-type flipflop as a
divide by two circuit. If your clocks needs to be separated in time, you can
use the circuit below.

Cl1 Cl2
| |
__ | |
+------| | .---. | .---. .---. |
| +----|& |-------|D Q|--+------|D Q|---------|D Q|--+
| | +--|__| Cl--|> | Cl--|> | Cl--|> |
| | | | /Q|o-+ | /Q|o-+ | /Q|o-+
| | | 74LS11 '---' | '---' | '---' |
| | | | | |
| | +--------------------+ | |
| +------------------------------------+ |
+----------------------------------------------------+
created by Andy´s ASCII-Circuit v1.24.140803 Beta www.tech-chat.de

The flopflips can be 1.5 ordinary, old fashioned 74LS74. You can reduce
chipcount by using one 74LS164 shiftregister instead.

petrus bitbyter
 
On Thu, 24 Mar 2005 23:41:46 +0100, petrus bitbyter wrote:
"Niall 84" <niall_heavey@yahoo.com> schreef in bericht

I am doing a project in college, Design of Switched capacitor filters
for a PCM Speech CODEC.

I am having trouble with the design of a BIPHASE clock which is meant
to drive the switches.

If your targets are edge triggered, you only need a D-type flipflop as a
divide by two circuit. If your clocks needs to be separated in time, you
can use the circuit below.

Cl1 Cl2
| |
__ | |
+------| | .---. | .---. .---. |
| +----|& |-------|D Q|--+------|D Q|---------|D Q|--+
| | +--|__| Cl--|> | Cl--|> | Cl--|> |
| | | | /Q|o-+ | /Q|o-+ | /Q|o-+
| | | 74LS11 '---' | '---' | '---' |
| | | | | |
| | +--------------------+ | |
| +------------------------------------+ |
+----------------------------------------------------+
created by Andy´s ASCII-Circuit v1.24.140803 Beta www.tech-chat.de

The flopflips can be 1.5 ordinary, old fashioned 74LS74. You can reduce
chipcount by using one 74LS164 shiftregister instead.

Why so much stuff? Why not just a Johnson counter?
Click to expand...

.--- C1
|
---- | ----
.-------|D Q|---+-------|D Q|------ C2
| C0 --|> | C0 ---|> |
| | /Q| | /Q|---.
| ---- ---- |
`---------------------------------'

Cheers!
Rich
 
"Rich Grise" <richgrise@example.net> schreef in bericht
news:pan.2005.03.25.00.34.22.940225@example.net...
On Thu, 24 Mar 2005 23:41:46 +0100, petrus bitbyter wrote:
"Niall 84" <niall_heavey@yahoo.com> schreef in bericht

I am doing a project in college, Design of Switched capacitor filters
for a PCM Speech CODEC.

I am having trouble with the design of a BIPHASE clock which is meant
to drive the switches.

If your targets are edge triggered, you only need a D-type flipflop as a
divide by two circuit. If your clocks needs to be separated in time, you
can use the circuit below.

Cl1 Cl2
| |
__ | |
+------| | .---. | .---. .---. |
| +----|& |-------|D Q|--+------|D Q|---------|D Q|--+
| | +--|__| Cl--|> | Cl--|> | Cl--|> |
| | | | /Q|o-+ | /Q|o-+ | /Q|o-+
| | | 74LS11 '---' | '---' | '---' |
| | | | | |
| | +--------------------+ | |
| +------------------------------------+ |
+----------------------------------------------------+
created by Andy´s ASCII-Circuit v1.24.140803 Beta www.tech-chat.de

The flopflips can be 1.5 ordinary, old fashioned 74LS74. You can reduce
chipcount by using one 74LS164 shiftregister instead.

Why so much stuff? Why not just a Johnson counter?

.--- C1
|
---- | ----
.-------|D Q|---+-------|D Q|------ C2
| C0 --|> | C0 ---|> |
| | /Q| | /Q|---.
| ---- ---- |
`---------------------------------'

Cheers!
Rich
Click to expand...
Does not work. Just try to analyze what happens when the flipflops starts
from 00. Two in time seperated clocks will look like this:
__ __ __
Cl1 __| |________| |________| |________
__ __ __
Cl2 ________| |________| |________| |__

With the Johnson counter one clock is shifted 90 degrees relative to the
other. (Which is ok if that is what the OP needs. "Bi-phase clock" is a
little ambigouos.)

petrus bitbyter
 
On Fri, 25 Mar 2005 04:31:54 +0100, petrus bitbyter wrote:
"Rich Grise" <richgrise@example.net> schreef in bericht
Click to expand...
Maybe this will help - the C0 signal is the same clock, to both:

.--- C1
|
---- | ----
.-------|D Q|---+-------|D Q|------ C2
| .--|> | .---|> |
| | | /Q| | | /Q|---.
| | ---- | ---- |
`----)---------------)------------'
| |
Click to expand...
C0 ------+---------------'

legend: --)-- = no connect

Does not work. Just try to analyze what happens when the flipflops
starts from 00. Two in time seperated clocks will look like this:
__ __ __
Cl1 __| |________| |________| |________
__ __ __
Cl2 ________| |________| |________| |__
Click to expand...
Yes it does, I have, and no they don't. And there are only two 'e' in
separated. ;-)

It does this:
_ _ _ _ _ _
C0 _| |_| |_| |_| |_| |_| |_
_______ _______
C1 _| |_______| |__
_______ ______
C2 _____| |_______|


With the Johnson counter one clock is shifted 90 degrees relative to the
other. (Which is ok if that is what the OP needs. "Bi-phase clock" is a
little ambigouos.)
Click to expand...
Thanks,
Rich
 
You must log in or register to reply here.

Welcome to EDABoard.com

Sponsor

Back
Top