how i can shitf the phahse 90° in high frequency

[ironjaycuttler]

well i have my local oscillator (2.25 Mhz) but i can't shift phase in 90° forward the problem is the high frequency i can't use Opams, so some here, have a circuit that can shift phase 90° forward, i can use transistors??? or maybe only RC circuits???? this signal i will input in one mixer so thanks for the help

 

[flatulent]

LC network

Run the signal through a low pass filter. Pick a large enough number of element type so that you get -270 degree phase shift which is the same as +90. A 8 pole with the cutoff slightly higher than your frequency will work.

You have some alternatives. Instead of advancing this signal, retard the other signal it is compared to by 90 degrees.

You can also generate the signal at 4x frequency and divide down in a Johnson counter which will give you outputs of all multiples of 90 degrees including zero. Since you are driving a mixer, you can use the square waves directly.

 

[HO_220]

hi.
you can use branchline power splitter that have 90 degree and 180 degree phase shift for narrow band applications.
bests.

 

[plishkin@zarya-k.ru]

well i have my local oscillator (2.25 Mhz) but i can't shift phase in 90° forward the problem is the high frequency i can't use Opams

2.25 Mhz is not so high.
You can use current feedback amplifier (AD9617 for example from Analog Devices)
But it's expensive.

As noted above you also should use a filter for fhase shift.

 

[artem]

Another approach to RC low pass filter is to use delay wire . It is about to introduce the 0.111 msec delay but RC filter is simpler .
2 order Butterworth low pass filter will give you 90 % phase delay output while gain at -3 db .

 

[ironjaycuttler]

thanks for your help, i will try to use the filter because is a project that i have here in mexico and i must use the most cheap device that i can found for the filter i can use ceramic capacitor???? or another type???

 

[jupitorcuu1]

use a 90degree length microstrip line after the output

 

[vfone]

jupitorcuu1 this was a good one. A microstrip transmission line at 2.25MHz it will have 19 meters!!!
I do prefer the LPF approach

 

[ironjaycuttler]

well i probed this circuit that i uploaded, well the problem is that only i have chance in phase 15° no more so what i can do???? and the output have much noise the transistor that i'm using is BF199 and u can see the R and C that i'm using so pls suggestions and the frequency is 2.25 Mhz (oscillator) and this siginal 90° forward i will put in one mixer

 

[artem]

I think your circuit is not right designed .
I will assume that your oscillator provides DC offset
at output so , you do not need to supply trans input with DC .
- remove C2
- connect C1 as one side to trans base
and second side to ground
- calculate the C1 and R1 (for easy calc use filter lab)
- get output signal from trans emitter .
- note that emitter resistr will affect the transistor input base to ground resistance for LPF (for typical trans it will give about 60-80 KOh) so your 1st order LPF output resistance must be 10 times less 5-6 KOhm

The circuit described will give you 45 degree phase
delay compared with input and gain loss of -3DB

Use 2 serially conneected ssuch circuits and you will have total 90 degree phase shift . You do not have to usse the repeater scheme , to compensate gain
get the output signal from second trans collector
connected to the power via resistor . The resistor value must be Rcoll ~= 2*Remit to compensate the gain loss in LPFs .

To be able to calculate the filter component characters , just download the filterlab from Microchip .

 

[ironjaycuttler]

hello another time thanks for the help, well here i upload my oscillator circuit the problem that i have is this the out put drop when i put a charge in this case the filter low pass, for example my output frequency is ok 2.25 Mhz and y voltage is 2.53 Vpp but when i put a charge my voltage frop 2.031 volts what i can do??? i must put a little driver??? any circuits?? and thanks for the advance in the last post well i put a RC circuits low pass filter and i can chance the phase in 45° so i need another 45° can u explain me the last part for i can obtain the another 45° with output of collector pls and the filter lab i couldn't donwload so another URL when i can donwload pls thanks for the help and here is the link where u can find my investigation



**broken link removed**